共用题干 Lack of Oxygen Delayed the Rise of Animals on EarthScientists have long speculated as to why animal species didn't flourish sooner,once sufficient oxygen covered the Earth's surface. Animals began to prosper at the end of the Proterozoic period,about
题目
共用题干
Lack of Oxygen Delayed the Rise of Animals on Earth
Scientists have long speculated as to why animal species didn't flourish sooner,once sufficient oxygen covered the Earth's surface. Animals began to prosper at the end of the Proterozoic period,about 800 million years ago-but what about the billion-year stretch before that,when most researchers think there also was plenty of oxygen?
Well,it seems the air wasn't so great then,after all.
In a study published Oct. 3 1 in Science,Yale researcher Noah Planavsky and his colleagues found that oxygen levels during the"boring billion"period were only 0.1%of what they are today .In other words,Earth's atmosphere couldn't have supported a diversity of creatures,no matter what genetic advancements were poised to occur.
"There is no question that genetic and ecological innovation must ultimately be behind the rise of animals,but it is equally unavoidable that animals need a certain level of oxygen,"said Planavsky,colead author of the research along with Christopher Reinhard of the Georgia Institute of Technology.“We're providing the first evidence that oxygen levels were low enough during this period to potentially prevent the rise of animals."
The scientists found their evidence by analyzing chromium(Cr)isotopes in ancient sediments from China,Australia,Canada,and the United States.Chromium is found in the Earth's continental crust,and chromium oxidation is directly linked to the presence of free oxygen in the atmosphere.
Specifically,the team studied samples deposited in shallow,iron-rich ocean areas,near the shore.They compared their data with other samples taken from younger locales known to have higher levels of oxygen.
Oxygen's role in controlling the first appearance of animals has long vexed scientists."We were missing the right approach until now,"Planavsky said."Chromium gave us the proxy."
Previous estimates put the oxygen level at 40%of today's conditions during pre-animal times. leaving open the possibility that oxygen was already plentiful enough to support animal life.
In the new study,the researchers acknowledged that oxygen levels were"highly dynamic"in the early atmosphere,with the potential for occasional spikes. However,they said,"It seems clear that there is a first-order difference in the nature of Earth surface Cr cycling"before and af- ter the rise of animals.
"If we are right,our results will really change how people view the origins of animals and other complex life,and their relationships to the co-evolving environment,"said co-author Tim
Lyons of the University of California-Riverside."This could be a game changer."
"There's a lot'of interest right now in a broader discussion surrounding the role that environ- mental stability played in the evolution of complex life,and we think our results are a significant contribution to that,"Reinhard said.
Lack of Oxygen Delayed the Rise of Animals on Earth
Scientists have long speculated as to why animal species didn't flourish sooner,once sufficient oxygen covered the Earth's surface. Animals began to prosper at the end of the Proterozoic period,about 800 million years ago-but what about the billion-year stretch before that,when most researchers think there also was plenty of oxygen?
Well,it seems the air wasn't so great then,after all.
In a study published Oct. 3 1 in Science,Yale researcher Noah Planavsky and his colleagues found that oxygen levels during the"boring billion"period were only 0.1%of what they are today .In other words,Earth's atmosphere couldn't have supported a diversity of creatures,no matter what genetic advancements were poised to occur.
"There is no question that genetic and ecological innovation must ultimately be behind the rise of animals,but it is equally unavoidable that animals need a certain level of oxygen,"said Planavsky,colead author of the research along with Christopher Reinhard of the Georgia Institute of Technology.“We're providing the first evidence that oxygen levels were low enough during this period to potentially prevent the rise of animals."
The scientists found their evidence by analyzing chromium(Cr)isotopes in ancient sediments from China,Australia,Canada,and the United States.Chromium is found in the Earth's continental crust,and chromium oxidation is directly linked to the presence of free oxygen in the atmosphere.
Specifically,the team studied samples deposited in shallow,iron-rich ocean areas,near the shore.They compared their data with other samples taken from younger locales known to have higher levels of oxygen.
Oxygen's role in controlling the first appearance of animals has long vexed scientists."We were missing the right approach until now,"Planavsky said."Chromium gave us the proxy."
Previous estimates put the oxygen level at 40%of today's conditions during pre-animal times. leaving open the possibility that oxygen was already plentiful enough to support animal life.
In the new study,the researchers acknowledged that oxygen levels were"highly dynamic"in the early atmosphere,with the potential for occasional spikes. However,they said,"It seems clear that there is a first-order difference in the nature of Earth surface Cr cycling"before and af- ter the rise of animals.
"If we are right,our results will really change how people view the origins of animals and other complex life,and their relationships to the co-evolving environment,"said co-author Tim
Lyons of the University of California-Riverside."This could be a game changer."
"There's a lot'of interest right now in a broader discussion surrounding the role that environ- mental stability played in the evolution of complex life,and we think our results are a significant contribution to that,"Reinhard said.
The study revealed that chromium found in Earth's continental crust remained stable before and after the rise of animals.
A:.Right
B: Wrong
C: Not mentioned
A:.Right
B: Wrong
C: Not mentioned
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更多“共用题干 Lack of Oxygen Delayed the Rise of Animals on EarthScientists have long speculated as to why animal species didn't flourish sooner,once sufficient oxygen covered the Earth's surface. Animals began to prosper at the end of the Proterozoic period,about”相关问题
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第1题：
Animals other than humans have not developed communications comparable to human language. But is it possible that other animals have the capacity to learn a language if they are adequately taught? Obviously, this is a fascination notion. The idea of communicating directly with another species has long been a part of human folklore and children’s fantasies. But on a scientific level, the question of whether animals can learn a language is important primarily because it relates to the controversy()between the cognitive and the learning approaches to language. If language is dependent on and is actually an outgrowth of the intellectual structure of the human mind, there is the strong supposition that only humans are capable of using language. Therefore, Noam Chomsky and other psycholinguists have argued that only humans can learn a language, while most behaviorists feel that with sufficient patience it should be possible to teach an animal some sort of language. Although the two schools of thought clearly differ on this point, it is not really a crucial test of the two theories. If a chimpanzee can master a simple language all it would mean is that the chimp’s intellectual capacity and brain structure are more similar to ours than we thought. It would not necessarily imply that our intellectual structure is unimportant in our own mastery of language. Thus, teaching an animal language is an impressive demonstration of the power of learning techniques, but it is not evidence that language is developed entirely through learning.On the other hand, the question of whether other animals can learn a language is fascination in its own right, aside from its value as a test of the two theories of language development. Accordingly, whatever one’s position on the theoretical dispute, we must consider training an animal to use language a dramatic accomplishment.
36.Which of the following statements is the view of psycholinguists?
A. The cognitive view of language learning says that only human beings can learn language because it is an outgrowth of the structure of the human mind.
B. Other animals simply could master a language.
C. The animals intellectual capacity is much better than human beings.
D. Language is developed by learning.
37.The behaviorists’ view is that __________.
A. language is actually an outgrowth of intellectual structure of the animal’s mind
B. animals have not developed communications system
C. given enough patience, a man should be able to teach an animal some sort of language
D. only human beings can learn language
38.That an animal can master a simple language means that __________.
A. human’s intellectual structure is not important
B. animals’ intellectual capacity and brain structure are more similar to the humans’
C. the learning techniques are much more important
D. language is developed completely by learning
39.The main idea of paragraph two is ___________.
A. teaching a chimp language is not crucial test of the two theories
B. their brain structure is not similar to human
C. using various methods to let the chimp master a language
D. training a nonhuman to use language is an amazing accomplishment
40.The best title for this passage would be _________.
A. Animals’ language
B. Human’s language
C. Teaching Animals’ Language
D. Can Other Animals Acquire Language?
参考答案：
36.B37.A38.D39.C40.C
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第2题：
If cloned animals could be used as organ donors, ().
A、people don’t have to worry about cloning twins for transplants
B、raising animals such as pigs can help solve the problem
C、the human body attacks and destroys tissue from other species
D、it may be more efficient to produce such animals by cloning than by cur
参考答案：ABD
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第3题：
It was long supposed ____ the main difference between animals and plants was that animals could move about.
A: which
B: this
C: that
D: because
参考答案：C
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第4题：
Which statement about entry into a space that has been sealed for a long time is TRUE ________．
A.A tank that has been used to carry hazardous liquids should be tested for oxygen content，toxicity，and explosive gases
B.You can safely enter the space without a breathing apparatus if the oxygen content exceeds 14%
C.The natural ventilation through the installed vents is sufficient to provide the proper oxygen content
D.The heat of the sun on upper ballast tanks，such as in a bulk carrier，may generate carbon monoxide
正确答案：A
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第5题：
Many kinds of animals have vanished from the earth.A:developed
B:disappeared
C:linked
D:renewed答案：B解析：vanish“消灭，消失”。本句意思是：很多种动物从地球上消失了。disappear也是“消失”的意思。 -
第6题：
共用题干
第三篇
Longer Lives for Wild Elephants
Most people think of zoos as safe places for animals,where struggles such as having difficulty finding
food and avoiding predators（猛兽）don't exist. Without such problems,animals in zoos should live to a ripe
（成熟的）old age.
But that may not be true for the largest land animals on Earth.Scientists have known that elephants in
zoos often suffer from poor health.Sometimes,they even become unable to have babies.
To learn more about how captivity（圈养）affects elephants, a team of international scientists compared
the life spans of female elephants born in zoos with female elephants living outdoors in their native lands.
Zoos keep detailed records of all the animals in their care,documenting factors such as birth dates,illnes-
ses,weight and death.These records made it possible for the researchers to analyze 40 years of data on 800
African and Asian elephants in zoos across Europe.The scientists compared the life spans of the zoo-born fe-
male elephants with the life spans of thousands of wild female elephants in Africa and Asian elephants that
work in logging camps（伐木场）, over approximately the same time period.
The team found that female African elephants born in zoos lived an average of 16.9 years. Their wild
counterparts who died of natural causes lived an average of 56 years一more than three times as long. Female
Asian elephants followed a similar pattern. In zoos,they lived 18.9 years,while those in the logging camps
lived 41.7 years.
Scientists don't know yet why wild elephants seem to get on so much better than their zoo-raised coun-
terparts.Georgia Mason,a biologist at the University of Guelph in Canada who led the study,thinks stress
and obesity（肥胖症）may be to blame. Zoo elephants don't get the same kind of exercise they would in the
wild,and most are very fat. Social lives of elephants are also much different in zoos than in the wild,where
they live in large herds and family groups.
The study raises some questions about acquiring more elephants to keep in zoos.While some threatened
and endangered species living in zoos reproduce（生殖）successfully and maintain healthy populations,that
doesn't appear to be the case with elephants.Unlike other animals in zoos,zoo-raised elephants
A:live a long life
B:give birth to many babies
C:develop poor health
D:have difficulty getting food答案：C解析：由文章第二段第二句话可知答案。
由文章第三段可知，是动物园记录他们所照顾的大象的详细信息，而不是科学家们。
由第四段两组数据对比可知，在动物园出生的雌象比野生的寿命短很多，即死得更早。
由第五段内容可知，圈养的大象之所以短命是因为它们不是成群大家庭生活的。
最后一段暗示大象和其他适合圈养的动物不一样、它需要野外生活，因此圈养大象可 能是不明智的。第5部分：补全短文 -
第7题：
共用题干
第二篇
Human and the Earth
In terms of the evolution of life on Earth,human beings have just arrived.Despite their shori time on Earth,however,people have brought about enormous changes to the surface of the planet一changes far out of proportion to the interval of time they have occupied it.
People have more control over their surroundings than any other species on Earth.With the combination of intelligence and manual skill(allowing us to make and use tools),people have found ways to use plant and animal resources,mineral ores,fuels,and many other materials and resources from the Earth.
As the number of people on Earth increases,it becomes increasingly difficult for the population to survive on the resources of the land.The amount of land is limited.Although agricultural production can be increased by use of machinery such as tractors and the addition of fertilizer,the land ultimately can produce only so much food and no more.
As the human population grows,people consume more.Clearly,some locations on Earth already have too many people;in many of these areas,future increases will surely bring about more poverty and suffering. Yet people in rich nations use proportionally far more of the available resources than people in poorer nations.As they consume these resources without restraint,they also waste large amounts of them.
People are only a very small fraction of all the living things on the planet.Yet their numbers create a drain on resources that can't be renewed.For example,the amount of water on Earth is limited,this water is cleaned through natural processes.However,the natural processes for filtering water can clean only a certain amount of water by removing the pollution.Likewise,a limited amount of petroleum can be found under the Earth's surface.Petroleum is a valuable resource.Should people use it up to manufacture petrol for automobiles?As people work to control the planet and make life comfortable,are they using up resources that are needed for their survival?Why have people more control over their surroundings than any other species on Earth?
A:Because of their intelligence and manual skill.
B:Because they can use plant and animal resources,mineral ores and fuels.
C:Because they are cleverer than any other animals on Earth.
D:Both A and B.答案：D解析：文章第一段第一句话提到“就地球上生命的进化而言，人类是姗姗来迟者”，因此比较而言，人类的历史并不长。选项A是正确的。
从文章第二段第二句话“With the combination of intelligence and manual skill...”我们知道选项A和B都是正确的，因此选择D项。
文章第三段提到，土地的总量是有限的。虽然使用拖拉机等机械和施用化肥可以提高农业产量，但是土地最终所能产出的粮食只有那么多，不会再增加。因此只有选项C是正确的。
文章第四段第三句说富裕国家的人们所使用的能源在比例上远远大于贫穷国家的人们。选项C中提到的“发达国家的人们”最符合题意。
根据文章最后一段关于资源的描述我们可以发现选项A、B、C都是正确的，只有选项D的表述错误，因此选择D项。 -
第8题：
共用题干
Lack of Oxygen Delayed the Rise of Animals on Earth
Scientists have long speculated as to why animal species didn't flourish sooner,once sufficient oxygen covered the Earth's surface. Animals began to prosper at the end of the Proterozoic period,about 800 million years ago-but what about the billion-year stretch before that,when most researchers think there also was plenty of oxygen?
Well,it seems the air wasn't so great then,after all.
In a study published Oct. 3 1 in Science,Yale researcher Noah Planavsky and his colleagues found that oxygen levels during the"boring billion"period were only 0.1%of what they are today .In other words,Earth's atmosphere couldn't have supported a diversity of creatures,no matter what genetic advancements were poised to occur.
"There is no question that genetic and ecological innovation must ultimately be behind the rise of animals,but it is equally unavoidable that animals need a certain level of oxygen,"said Planavsky,colead author of the research along with Christopher Reinhard of the Georgia Institute of Technology.“We're providing the first evidence that oxygen levels were low enough during this period to potentially prevent the rise of animals."
The scientists found their evidence by analyzing chromium(Cr)isotopes in ancient sediments from China,Australia,Canada,and the United States.Chromium is found in the Earth's continental crust,and chromium oxidation is directly linked to the presence of free oxygen in the atmosphere.
Specifically,the team studied samples deposited in shallow,iron-rich ocean areas,near the shore.They compared their data with other samples taken from younger locales known to have higher levels of oxygen.
Oxygen's role in controlling the first appearance of animals has long vexed scientists."We were missing the right approach until now,"Planavsky said."Chromium gave us the proxy."
Previous estimates put the oxygen level at 40%of today's conditions during pre-animal times. leaving open the possibility that oxygen was already plentiful enough to support animal life.
In the new study,the researchers acknowledged that oxygen levels were"highly dynamic"in the early atmosphere,with the potential for occasional spikes. However,they said,"It seems clear that there is a first-order difference in the nature of Earth surface Cr cycling"before and af- ter the rise of animals.
"If we are right,our results will really change how people view the origins of animals and other complex life,and their relationships to the co-evolving environment,"said co-author Tim
Lyons of the University of California-Riverside."This could be a game changer."
"There's a lot'of interest right now in a broader discussion surrounding the role that environ- mental stability played in the evolution of complex life,and we think our results are a significant contribution to that,"Reinhard said.Tim Lyons liked to play computer games in his spare time.
A:Right
B: Wrong
C:Not mentioned答案：C解析：题干说研究发现动物的大量繁殖发生在比原生代时期更早的时候。从文章第一段中“Animals began to prosper at the end of...”可知，动物的大量繁殖是在原生代末翔，而不是比原生代更早。故题干叙述错误，选B。
题干意思是许多研究者认为氧气的含量在史前动物时代是非常高的。根据文章第一段“...the billion-year stretch before that,when most researchers think there also was plenty of oxygen?”可知，大量研究者认为，在原生代之前的十亿年间，地球上存在着大量的氧气。而“pre-animal times”也就是“the end of the Proterozoic period"。
题干意思是，那个研究小组的研究资金是由几个研究机构提供的。通读全文可知，文章并没有提到该信息。故选C。
题干说遗传的进化会引发动物的大量繁殖。根据文章第四段“There is no question that... that animals need a certain level of oxygen”可知，毫无疑问的是，遗传的进化和生态的进化是支持动物大量繁殖的最根本的原因，但同样不可避免的是，动物的繁殖也是需要一定量的氧气的。因此题干叙述正确，选A。
题干说研究中所研究的样本是从海洋中采集的。从文章第六段可知，研究采集了用于对比分析的两种样本，一个是从海洋地区采集的，而另一个是从含氧量较高地区采集的。因此题干叙述错误，选B。
题干意思是，研究揭示，在陆地表面所发现的格在动物大量繁殖前后是保持不变的。根据文章第八段“It seems clear that there is a first-order difference in the nature of Earth surface Cr cycling' before and after the rise of animals.”可知，在动物大量繁殖前后，地球表面上铬的循环会出现差异。故本题选B。
题干说Tim Lyons空闲时间喜欢打电脑游戏。文章并没有提到该研究者的业余爱好，故选C。 -
第9题：
共用题干
Lack of Oxygen Delayed the Rise of Animals on Earth
Scientists have long speculated as to why animal species didn't flourish sooner,once sufficient oxygen covered the Earth's surface. Animals began to prosper at the end of the Proterozoic period,about 800 million years ago-but what about the billion-year stretch before that,when most researchers think there also was plenty of oxygen?
Well,it seems the air wasn't so great then,after all.
In a study published Oct. 3 1 in Science,Yale researcher Noah Planavsky and his colleagues found that oxygen levels during the"boring billion"period were only 0.1%of what they are today .In other words,Earth's atmosphere couldn't have supported a diversity of creatures,no matter what genetic advancements were poised to occur.
"There is no question that genetic and ecological innovation must ultimately be behind the rise of animals,but it is equally unavoidable that animals need a certain level of oxygen,"said Planavsky,colead author of the research along with Christopher Reinhard of the Georgia Institute of Technology.“We're providing the first evidence that oxygen levels were low enough during this period to potentially prevent the rise of animals."
The scientists found their evidence by analyzing chromium(Cr)isotopes in ancient sediments from China,Australia,Canada,and the United States.Chromium is found in the Earth's continental crust,and chromium oxidation is directly linked to the presence of free oxygen in the atmosphere.
Specifically,the team studied samples deposited in shallow,iron-rich ocean areas,near the shore.They compared their data with other samples taken from younger locales known to have higher levels of oxygen.
Oxygen's role in controlling the first appearance of animals has long vexed scientists."We were missing the right approach until now,"Planavsky said."Chromium gave us the proxy."
Previous estimates put the oxygen level at 40%of today's conditions during pre-animal times. leaving open the possibility that oxygen was already plentiful enough to support animal life.
In the new study,the researchers acknowledged that oxygen levels were"highly dynamic"in the early atmosphere,with the potential for occasional spikes. However,they said,"It seems clear that there is a first-order difference in the nature of Earth surface Cr cycling"before and af- ter the rise of animals.
"If we are right,our results will really change how people view the origins of animals and other complex life,and their relationships to the co-evolving environment,"said co-author Tim
Lyons of the University of California-Riverside."This could be a game changer."
"There's a lot'of interest right now in a broader discussion surrounding the role that environ- mental stability played in the evolution of complex life,and we think our results are a significant contribution to that,"Reinhard said.The study discovered the rise of animals occurred earlier than the Proterozoic period.
A: Right
B: Wrong
C: Not mentioned答案：B解析：题干说研究发现动物的大量繁殖发生在比原生代时期更早的时候。从文章第一段中“Animals began to prosper at the end of...”可知，动物的大量繁殖是在原生代末翔，而不是比原生代更早。故题干叙述错误，选B。
题干意思是许多研究者认为氧气的含量在史前动物时代是非常高的。根据文章第一段“...the billion-year stretch before that,when most researchers think there also was plenty of oxygen?”可知，大量研究者认为，在原生代之前的十亿年间，地球上存在着大量的氧气。而“pre-animal times”也就是“the end of the Proterozoic period"。
题干意思是，那个研究小组的研究资金是由几个研究机构提供的。通读全文可知，文章并没有提到该信息。故选C。
题干说遗传的进化会引发动物的大量繁殖。根据文章第四段“There is no question that... that animals need a certain level of oxygen”可知，毫无疑问的是，遗传的进化和生态的进化是支持动物大量繁殖的最根本的原因，但同样不可避免的是，动物的繁殖也是需要一定量的氧气的。因此题干叙述正确，选A。
题干说研究中所研究的样本是从海洋中采集的。从文章第六段可知，研究采集了用于对比分析的两种样本，一个是从海洋地区采集的，而另一个是从含氧量较高地区采集的。因此题干叙述错误，选B。
题干意思是，研究揭示，在陆地表面所发现的格在动物大量繁殖前后是保持不变的。根据文章第八段“It seems clear that there is a first-order difference in the nature of Earth surface Cr cycling' before and after the rise of animals.”可知，在动物大量繁殖前后，地球表面上铬的循环会出现差异。故本题选B。
题干说Tim Lyons空闲时间喜欢打电脑游戏。文章并没有提到该研究者的业余爱好，故选C。 -
第10题：
An Essential Scientific Process
All life on the earth depends upon green plants. Using sunlight, theplants produce their own food. Then animals feed upon the plants. They take inthe nutrients the plants have made sted. But that’s not all.Sunlight also helps a plant produce oxygen. Some of the oxygen is used by theplant, but a plant usually produces me oxygen than it uses. The excess oxygenis necessary f animals other ganisms to live.
The process of changing light into food oxygen is calledphotosynthesis. Besides light energy from the sun, plants also use water carbon dioxide. The water gets to the plant through its roots. The carbondioxide enters the leaves through tiny openings called stomata. The carbondioxide travels to chloplasts, special cells in the bodies of green plants.This is photosynthesis takes place. Chloplasts contain the chlophyllsthat give plants their green col. The chlophylls are the molecules thattrap light energy. The trapped light energy changes water carbon dioxide toproduce oxygen a simple sugar called glucose.
Carbon dioxide oxygen move into out of the stomata. Watervap also moves out of the stomata. Me than 90 percent of water a planttakes in through its roots escapes through the stomata. During the daytime, thestomata of most plants are open. This allows carbon dioxide to enter the leavesf photosynthesis. As night falls, carbon dioxide is not needed. The stomataof most plants close. Water loss stops.
If photosynthesis ceased, there would be little food other ganicmatter on the earth. Most ganisms would disappear. The earth’s atmospherewould no longer contain oxygen. Photosynthesis is essential f life on ourplanet.
词汇：
nutrient n.营养物
ganism n.生物体，有机体
carbon dioxide n.二氧化碳
chloplast n.叶绿体
molecule n.分子
vap n.水蒸气
oxygen n.氧气
photosynthesis n.光合作用
chlophyll n.叶绿素
glucose n.葡萄糖
cease v.停止
注释：
1.Then animals feed upon the plants.动物以植物为食。
练习：
5.Another good title f this passage would be
A.Oxygen Carbon Dioxide.
B.Plants Their Roots.
C.How Photosynthesis Wks.
D.Why Our Earth Needs Water.答案：C解析：5.C 文章的主题是光合作用的基本原理，因此选项C。A、B项在文中有提及，但不是主旨，D项与本文无关 -
第11题：
An Essential Scientific Process
All life on the earth depends upon green plants. Using sunlight, theplants produce their own food. Then animals feed upon the plants. They take inthe nutrients the plants have made sted. But that’s not all.Sunlight also helps a plant produce oxygen. Some of the oxygen is used by theplant, but a plant usually produces me oxygen than it uses. The excess oxygenis necessary f animals other ganisms to live.
The process of changing light into food oxygen is calledphotosynthesis. Besides light energy from the sun, plants also use water carbon dioxide. The water gets to the plant through its roots. The carbondioxide enters the leaves through tiny openings called stomata. The carbondioxide travels to chloplasts, special cells in the bodies of green plants.This is photosynthesis takes place. Chloplasts contain the chlophyllsthat give plants their green col. The chlophylls are the molecules thattrap light energy. The trapped light energy changes water carbon dioxide toproduce oxygen a simple sugar called glucose.
Carbon dioxide oxygen move into out of the stomata. Watervap also moves out of the stomata. Me than 90 percent of water a planttakes in through its roots escapes through the stomata. During the daytime, thestomata of most plants are open. This allows carbon dioxide to enter the leavesf photosynthesis. As night falls, carbon dioxide is not needed. The stomataof most plants close. Water loss stops.
If photosynthesis ceased, there would be little food other ganicmatter on the earth. Most ganisms would disappear. The earth’s atmospherewould no longer contain oxygen. Photosynthesis is essential f life on ourplanet.
词汇：
nutrient n.营养物
ganism n.生物体，有机体
carbon dioxide n.二氧化碳
chloplast n.叶绿体
molecule n.分子
vap n.水蒸气
oxygen n.氧气
photosynthesis n.光合作用
chlophyll n.叶绿素
glucose n.葡萄糖
cease v.停止
注释：
1.Then animals feed upon the plants.动物以植物为食。
练习：
2.Which of the following does not move through a plant’s stomata?
A.Carbon dioxide.
B.Water vap.
C.Oxygen.
D.Food.答案：D解析：2.D 从第三段的第一、二句得知，二氧化碳、氧气和水蒸气都能从气孔中通过，唯一一个没有提到的是food“养分、食物”，因此该题选D项。 -
第12题：
单选题Why does life on earth depend much on the oceans?ASea plants produce most of the oxygen in the atmosphere.
BCarbon dioxide is converted into oxygen in oceans.
CThe oceans provide an invaluable food resource.
DProductivity of fisheries can feed 80 million people.
正确答案： B解析：
录音的首句指出地球上的生命最终都要依靠覆盖地球71%的海洋，其中的原因是广阔的水域提供了大气层中大部分的氧气，同时微型植物每天吸收数百万吨的二氧化碳(These vast basins of water provide most of the oxygen in our atmosphere, and microscopic plants absorb millions of tons of carbon dioxide each day.)，还有就是海洋也含有珍贵的食物资源，每天通过渔业提供八千万公吨的食物(The seas also hold a precious food resource, providing 80 million metric tons of food a year through fishing)，所以只有C项正确。 -
第13题：
阅读理解There is no doubt that man is a member of the animal kingdom.Anyone who has thought about this fact seriously must have wondered how it has come about that man has achieved a position so supreme(最高的) among the myriad(无数的) kinds of animal life.Two characteristics of man, in comparison with all other animals, that stand out above all others are the creation and use of tools and the development and use of language.Since no other animals have achieved these abilities, it must be assumed that man’s evolutionary development led to his capacity to create and use tools and to devise and use language.
Once these abilities and practices evolved, they probably became driving forces in the further evolution of man.Those members of the species who become most proficient(精通的) in the fabrication of tools and in the command of language and thought would tend to survive and maintain their kind for good, at the expense of those of lesser ability.
11.Which of the following statements best expresses the main idea of the passage?()
A.Tools and language are either the effects or the causes of human evolution.
B.No other animals have achieved human abilities.
C.Among the animals, only man is able to use tools and language.
D.Man owns his capacity to making use of tools and language.
12.“Animal kingdom” in the passage refers to ().
A.the place where all animals live
B.the animal society
C.all kinds of animals, including man
D.the forest with animals
13.One important condition for man’s evolution is() .
A.the animal kingdom
B.a supreme position
C.the myriad kinds
D.his natural capacity
14.The phrase “come about” in the passage is likely to mean ________.
A.happened
B.appeared
C.arrived
D.succeeded
15.The last sentence suggests that() .
A.those of lesser ability would be very expensive
B.in order to survive, man has to sacrifice some other animals
C.those who become proficient in making tools can speak well
D.language and thought could be acquired by man
参考答案：ACDAB
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第14题：
Most animals have little connection with animals of different kind, unless they hunt them for food. Sometimes, however, two kinds of animals come together in a partnership ( 伙伴关系 ) which does good to both of them. You may have noticed some birds sitting on the backs of sheep. This is not because they want a ride, but because they find easy food in the parasites (寄生虫 ) on sheep. The sheep allow the birds to do so because they remove the cause of discomfort. So although they can manage without each other, they do better together.
Sometimes an animal has a plant partner. The relationship develops until the two partners cannot manage without each other. This is so in the corals ( 珊瑚 ) of the sea. In their skins they have tiny plants act as "dustman", taking some of the waste products form. the corals and giving in return oxygen which the animal needs to breathe. If the plants are killed, or are ever prevented from lighting so that they cannot live normally, the corals will die.
1、Some birds like to sit on a sheep because ( ).
A、they can eat its parasites
B、 they depend on the sheep for existence
C、 they enjoy traveling with the sheep
D、 they find the position most comfortable
2、The underlined word "they" in the last sentence of the first paragraph refers to ( ).
A、birds and parasites
B、birds and sheep
C、parasites and sheep
D、sheep, birds and parasites
3、What does the second paragraph mainly discuss? ( )
A、Some animals and plants depend on each other for existence.
B、 Some animals and plants develop their relationship easily.
C、 Some plants depend on each other for foo
D、 Some animals live better together.
4、What does this article talk about? ( )
A、Two kinds of animals for a partnership.
B、Most animals only have connection with animals.
C、The connection between the living things.
D、Corals have some connection with plants.
正确答案：1A 2B 3A 4C
-
第15题：
We now know that about ____ of all the kinds of seaweed are animals.
A: one four
B: once four
C: once fourth
D: one fourth
参考答案：D
-
第16题：
Which statement about entering into a tank which has been sealed for a long time is TRUE ________．
A.The tank should be tested only once to ensure the oxygen content is at least 14% before entry
B.The tank must be tested at frequent intervals to ensure that hazardous gasses have not regenerated
C.The tank need not be tested for oxygen content if it is ventilated for more than 24 hours
D.If the oxygen content tests at less than 12% you should wear an approved gas mask
正确答案：B
-
第17题：
共用题干
The world has got rainforests which cover 7% of the earth's surface.They grow around the earth's equator in South America,Central America,Africa,Southeast Asia,and Australia. Rainforests are important.(46)______.These rainforests are wet and warm.They get more than two meters of rain each year,and temperatures are usually between 24℃and 27℃．(47)______. Each area has a different environment with different plants,trees and animals.
(48)______.Every day a part of the rainforest,the same size as a football field,is destroyed because of human activities.(49)______,people cut down trees to make plantations to grow food,to get minerals or metals out of the ground or to build more and more houses.(50) ______.Cutting down trees must be prohibited and wild animals must be protected.If people break these rules,they must be arrested and severely punished._________（47）
A:Therefore strict measures must be taken
B:They give the earth oxygen,and are the home for half of the world's animals and plants
C:Because of a growing population
D:Unfortunately,these rainforests are in danger
E:Tropical rainforests are home to tribal peoples who rely on their surroundings for food,shelter,and medicines
F: They are divided into four different areas答案：F解析：本题考查的是对上下文之间意义关系的理解和对文章细节的把握。根据上文内容此处应填写的是“它们给地球提供氧气，是世界上一半动植物的家园”。
本题考查的是对上下文之间意义关系的理解。根据下文此处内容是“雨林被分成不同的区域”。
本题考查的是对上下文之间意义关系的理解。根据下文内容这里应是 “不幸的是，这些雨林处于危险之中”。
本题考查的是对上下文之间意义关系的理解。根据下文内容，此处是“由于人口增加”。
本题考查的是对上下文之间意义关系的理解。根据上下文内容，此处是 “因此，必须采取严格的措施”。 -
第18题：
共用题干
Why India Needs Its Dying Vultures
The vultures（秃鹰）in question may look ugly and threatening , but the sudden sharp decline in three
species of India'S vultures is producing alarm rather than celebration,and it presents the world with a new
kind of environmental problem.The dramatic__________(51)in vulture numbers is causing widespread
disruption to people living in the__________(52)areas as the birds.It is also causing serious public health
problems__________(53)the Indian sub-continent.
While their reputation and appearance may be unpleasant to many Indians,vultures have___________(54)
played a very important role in keeping towns and villages all over India___________(55).It is because they
feed on dead cows.In India,cows are sacred animals and are___________(56) left in the open when they
die in thousands upon thousands every year.
The disappearance of the vultures has___________(57)an explosion in the numbers of wild dogs
feeding on the remains of these___________(58)animals. There are fears that rabies（狂犬症）may increase as
a result. And this terrifying disease may ultimately（最终）affect humans in the region,___________(59)wild
dogs are its main carriers.Rabies could also spread to other animal species, __________(60)an even
greater problem in the future.
The need for action is___________(61),so an emergency project has been launched to find a solution
to this serious vulture problem?Scientists are trying to___________(62)the disease causing the birds'
deaths and,if possible,develop a cure.
Large-scale vulture___________(63)were first noticed at the end of the l980s in India. A population
survey at that time showed that the three species of vultures had declined___________(64)over 90 per
cent. All three species are now listed as"critically endangered".As most vultures lay only single eggs and
___________(65)about five years to reach maturity,reversing their population decline will be a long and dif-
ficult exercise._________(54)
A:rarely
B:recently
C:seldom
D:long答案：D解析：由本段第一句“… but the sudden sharp decline in three species of India ' s vultures...”可缸 此处是说秃鹰数量急剧下降。
由空后的"as”可知此处是考查固定搭配hte same as (和……相同的）。这里是说“和这些鸟住在同一地区的 人。
此处只能填across(在……各处，遍及），此处across the Indian sub-continent 表示"整个 印度次大陆"。above（在……上方）with (伴随，和……一起），through（穿越）用在此处均不合适。
第一段说秃鹰的急剧减少是一种警示而非值得庆贺的事，这给当地居民的生活带来了 很大的不便并造成了新的环境问题。这说明秃鹰在保护该区的环境上作用很大，所以秃鹰 不会是很少（rarely/seldom）起作用，或最近（recently)才起作用。只有选long（长期以来一直） 起作用才合乎上下文的意思。
下文说秃鹰以牛的尸体为食，秃鹰的急剧减少，导致同样以牛的尸体为实物的野狗大量繁殖，而狗是狂犬病毒的主要携带者，所以说秃鹰的存在对整个印度城乡环境的清洁起了很 大的作用。其他选项均不符合题意。smelly意为“难闻的，有臭味的”。
文章说，在印度，牛是一种神圣的动物，每年有成千上万头牛死亡后尸体暴露在野外。既然是这样，这些牛的尸体就不会是偶尔（occasionally)、立即（immediately）或几乎不（hardly) 暴露在野外。所以traditionally（历来，传统上）是正确答案。
本段第一句表达的是因果关系。"The disappearance of the vultures”是因，"an explosion in the numbers of wild dogs feeding on the remains of...”是果。lead to（导致）可以表达因果关 系，所以选A。
联系上文可知此处的“these…animals”指的是前边的死去的牛。这里是说，以牛的尸体 为食的秃鹰大量减少后，同样以此为食的野狗数量激增。
前边讲这种可怕的疾病最终可能会影响人类，空后说野狗是这种疾病病毒的主要携带 者，可见前后为因果关系，前边为果，后边是因。since可以表示“因为”，符合语境。
由后边的“an even greater problem”并联系前文即可确定答案为D。
从后面的“an emergency project has been launched（已启动了应急方案）”可以推断出要 选的形容词是urgent (紧迫的）。
科学家们是在寻找引起秃鹰死亡的疾病，如果可能的话找到治愈方法。identify表示 “找到，发现”，符合语境。prove（证明）,test (测试）,check(核实，检查）不合语境。
本段说秃鹰数量急剧减少，其中三种已被列为濒危物种。本题选deaths，正好与本段后 面一句“All three species are now listed as 'critically endangered'.”所表达的意思相照应。本句 的意思是，大规模的秃鹰死亡于19世纪80年代末在印度首次被注意到。
在四个选项中，along, on,in明显不合适。by有“到……的程度”的意思。"...the three species of vultures had declined by over 90 per cent”的意思是“……三种秃鹰的数量减少了 90％以上”。
“花费或用多少时间”英语的常用表达法是“……take＋时间＋其他”。故take是正确答 案。consume指“消耗”，虽也可指消耗时间，但用在这儿不如take合适。 -
第19题：
共用题干
Lack of Oxygen Delayed the Rise of Animals on Earth
Scientists have long speculated as to why animal species didn't flourish sooner,once sufficient oxygen covered the Earth's surface. Animals began to prosper at the end of the Proterozoic period,about 800 million years ago-but what about the billion-year stretch before that,when most researchers think there also was plenty of oxygen?
Well,it seems the air wasn't so great then,after all.
In a study published Oct. 3 1 in Science,Yale researcher Noah Planavsky and his colleagues found that oxygen levels during the"boring billion"period were only 0.1%of what they are today .In other words,Earth's atmosphere couldn't have supported a diversity of creatures,no matter what genetic advancements were poised to occur.
"There is no question that genetic and ecological innovation must ultimately be behind the rise of animals,but it is equally unavoidable that animals need a certain level of oxygen,"said Planavsky,colead author of the research along with Christopher Reinhard of the Georgia Institute of Technology.“We're providing the first evidence that oxygen levels were low enough during this period to potentially prevent the rise of animals."
The scientists found their evidence by analyzing chromium(Cr)isotopes in ancient sediments from China,Australia,Canada,and the United States.Chromium is found in the Earth's continental crust,and chromium oxidation is directly linked to the presence of free oxygen in the atmosphere.
Specifically,the team studied samples deposited in shallow,iron-rich ocean areas,near the shore.They compared their data with other samples taken from younger locales known to have higher levels of oxygen.
Oxygen's role in controlling the first appearance of animals has long vexed scientists."We were missing the right approach until now,"Planavsky said."Chromium gave us the proxy."
Previous estimates put the oxygen level at 40%of today's conditions during pre-animal times. leaving open the possibility that oxygen was already plentiful enough to support animal life.
In the new study,the researchers acknowledged that oxygen levels were"highly dynamic"in the early atmosphere,with the potential for occasional spikes. However,they said,"It seems clear that there is a first-order difference in the nature of Earth surface Cr cycling"before and af- ter the rise of animals.
"If we are right,our results will really change how people view the origins of animals and other complex life,and their relationships to the co-evolving environment,"said co-author Tim
Lyons of the University of California-Riverside."This could be a game changer."
"There's a lot'of interest right now in a broader discussion surrounding the role that environ- mental stability played in the evolution of complex life,and we think our results are a significant contribution to that,"Reinhard said.Genetic advancements triggered the rise of animals.
A: Right
B: Wrong
C: Not mentioned答案：A解析：题干说研究发现动物的大量繁殖发生在比原生代时期更早的时候。从文章第一段中“Animals began to prosper at the end of...”可知，动物的大量繁殖是在原生代末翔，而不是比原生代更早。故题干叙述错误，选B。
题干意思是许多研究者认为氧气的含量在史前动物时代是非常高的。根据文章第一段“...the billion-year stretch before that,when most researchers think there also was plenty of oxygen?”可知，大量研究者认为，在原生代之前的十亿年间，地球上存在着大量的氧气。而“pre-animal times”也就是“the end of the Proterozoic period"。
题干意思是，那个研究小组的研究资金是由几个研究机构提供的。通读全文可知，文章并没有提到该信息。故选C。
题干说遗传的进化会引发动物的大量繁殖。根据文章第四段“There is no question that... that animals need a certain level of oxygen”可知，毫无疑问的是，遗传的进化和生态的进化是支持动物大量繁殖的最根本的原因，但同样不可避免的是，动物的繁殖也是需要一定量的氧气的。因此题干叙述正确，选A。
题干说研究中所研究的样本是从海洋中采集的。从文章第六段可知，研究采集了用于对比分析的两种样本，一个是从海洋地区采集的，而另一个是从含氧量较高地区采集的。因此题干叙述错误，选B。
题干意思是，研究揭示，在陆地表面所发现的格在动物大量繁殖前后是保持不变的。根据文章第八段“It seems clear that there is a first-order difference in the nature of Earth surface Cr cycling' before and after the rise of animals.”可知，在动物大量繁殖前后，地球表面上铬的循环会出现差异。故本题选B。
题干说Tim Lyons空闲时间喜欢打电脑游戏。文章并没有提到该研究者的业余爱好，故选C。 -
第20题：
共用题干
Lack of Oxygen Delayed the Rise of Animals on Earth
Scientists have long speculated as to why animal species didn't flourish sooner,once sufficient oxygen covered the Earth's surface. Animals began to prosper at the end of the Proterozoic period,about 800 million years ago-but what about the billion-year stretch before that,when most researchers think there also was plenty of oxygen?
Well,it seems the air wasn't so great then,after all.
In a study published Oct. 3 1 in Science,Yale researcher Noah Planavsky and his colleagues found that oxygen levels during the"boring billion"period were only 0.1%of what they are today .In other words,Earth's atmosphere couldn't have supported a diversity of creatures,no matter what genetic advancements were poised to occur.
"There is no question that genetic and ecological innovation must ultimately be behind the rise of animals,but it is equally unavoidable that animals need a certain level of oxygen,"said Planavsky,colead author of the research along with Christopher Reinhard of the Georgia Institute of Technology.“We're providing the first evidence that oxygen levels were low enough during this period to potentially prevent the rise of animals."
The scientists found their evidence by analyzing chromium(Cr)isotopes in ancient sediments from China,Australia,Canada,and the United States.Chromium is found in the Earth's continental crust,and chromium oxidation is directly linked to the presence of free oxygen in the atmosphere.
Specifically,the team studied samples deposited in shallow,iron-rich ocean areas,near the shore.They compared their data with other samples taken from younger locales known to have higher levels of oxygen.
Oxygen's role in controlling the first appearance of animals has long vexed scientists."We were missing the right approach until now,"Planavsky said."Chromium gave us the proxy."
Previous estimates put the oxygen level at 40%of today's conditions during pre-animal times. leaving open the possibility that oxygen was already plentiful enough to support animal life.
In the new study,the researchers acknowledged that oxygen levels were"highly dynamic"in the early atmosphere,with the potential for occasional spikes. However,they said,"It seems clear that there is a first-order difference in the nature of Earth surface Cr cycling"before and af- ter the rise of animals.
"If we are right,our results will really change how people view the origins of animals and other complex life,and their relationships to the co-evolving environment,"said co-author Tim
Lyons of the University of California-Riverside."This could be a game changer."
"There's a lot'of interest right now in a broader discussion surrounding the role that environ- mental stability played in the evolution of complex life,and we think our results are a significant contribution to that,"Reinhard said.Many researchers believe the oxygen level was high during pre-animal times.
A: Right
B: Wrong
C: Not mentioned答案：A解析：题干说研究发现动物的大量繁殖发生在比原生代时期更早的时候。从文章第一段中“Animals began to prosper at the end of...”可知，动物的大量繁殖是在原生代末翔，而不是比原生代更早。故题干叙述错误，选B。
题干意思是许多研究者认为氧气的含量在史前动物时代是非常高的。根据文章第一段“...the billion-year stretch before that,when most researchers think there also was plenty of oxygen?”可知，大量研究者认为，在原生代之前的十亿年间，地球上存在着大量的氧气。而“pre-animal times”也就是“the end of the Proterozoic period"。
题干意思是，那个研究小组的研究资金是由几个研究机构提供的。通读全文可知，文章并没有提到该信息。故选C。
题干说遗传的进化会引发动物的大量繁殖。根据文章第四段“There is no question that... that animals need a certain level of oxygen”可知，毫无疑问的是，遗传的进化和生态的进化是支持动物大量繁殖的最根本的原因，但同样不可避免的是，动物的繁殖也是需要一定量的氧气的。因此题干叙述正确，选A。
题干说研究中所研究的样本是从海洋中采集的。从文章第六段可知，研究采集了用于对比分析的两种样本，一个是从海洋地区采集的，而另一个是从含氧量较高地区采集的。因此题干叙述错误，选B。
题干意思是，研究揭示，在陆地表面所发现的格在动物大量繁殖前后是保持不变的。根据文章第八段“It seems clear that there is a first-order difference in the nature of Earth surface Cr cycling' before and after the rise of animals.”可知，在动物大量繁殖前后，地球表面上铬的循环会出现差异。故本题选B。
题干说Tim Lyons空闲时间喜欢打电脑游戏。文章并没有提到该研究者的业余爱好，故选C。 -
第21题：
共用题干
第三篇
Animal Testing Controversy
To paraphrase 18th-century statesman Edmund Burke,"All that is needed for the triumph of a misguided cause is that good people do nothing." One such cause now seeks to end biomedical research because of the theory that animals have rights ruling out their use in research.Scientists need to respond forcefully to animal rights advocates,whose arguments are confusing the public and thereby threatening advances in health knowledge and care.Leaders of the animal rights movement target biomedical research because it depends on public funding,and few people understand the process of health care research.Hearing allegations of cruelty to animals in research settings,many are perplexed that anyone would deliberately harm an animal.
For example,a grandmotherly woman staffing an animal rights booth at a recent street fair was distributing a brochure that encouraged readers not to use anything that comes from or is animals一no meat,no fur,no medicines.Asked if she opposed immunizations,she wanted to know if vaccines come from animal research.When assured that they do,she replied,"Then I would have to say yes."Asked what will happen when epidemics return,she said,"Don't worry,scientists will find some way of using computers."Such well-meaning people just don't understand.
Scientists must communicate their message to the public in a compassionate,understandable way一in human terms,not in the language of molecular biology.We need to make clear the connection between animal research and a grandmother's hip replacement,a father's bypass operation,a baby's vaccinations,and even a pet's shots.To those who are unaware that animal research was nee-- ded to produce these treatments,as well as new treatments and vaccines,animal research seems wasteful at best and cruel at worst.
Much can be done.Scientists could"adopt"middle school classes and present their own re-search.They should be quick to respond to letters to the editor,lest animal rights misinformation go unchallenged and acquire a deceptive appearance of truth.Research institutions could be opened to tours,to show that laboratory animals receive humane care.Finally,because the ultimate stakeholders are patients,the health research community should actively recruit to its cause not only well-known personalities such as Stephen Cooper,who has made courageous statements about the value of animal research,but all who receive medical treatment.If good people do nothing there is a real possibility that an uninformed citizenry will extinguish the precious embers of medical progress.The example of the grandmotherly woman is used to show the public's________
A:discontent with animal research
B:ignorance about medical science
C:indifference to epidemics
D:anxiety about animal rights答案：B解析：第一段中间提到“Scientists need to respond forcefully to animal rights advocates...”意思是科学家们需要采取行动回应这些动物权利的鼓吹者。这实际上就是一个呼吁，所以答案应该是A。
第一段最后一句说，被误导的人们“听到医学实验残忍对待动物的指控时，许多人都不明白为什么有人会故意伤害动物”。第二段举了被误导女士的例子，她反对用动物来做研究。第三段最后一句，这些人认为“动物实验说得好是浪费，说得不好是残忍”。A 内容不完整。inevitable：不可避免的；vicious：危险的，所以选项B正确。
该例子中，慈祥的妇人“encouraged readers not to use anything that comes from or is animals”，至于疫苗，如果来自动物她也抵制，认为流行病自有科学家们用计算机来解决。由此可见老人对科学的无知。第二段最后一句感叹“这些好心人根本就不明白”，所以答案为B。
根据关键词“challenge from animal rights advocates”以及“scientists should”, 可以在最后两段中找出作者向科学家们提出的建议都有助于他们与公众更好的交流。很明显选项A合理，选项B、C、D在文中没有提到，不正确。
最后一段“Finally,because the ultimate stakeholders are patients...Stephen Cooper, who has made courageous statements about the value of animal research”。从这句话我们知道，Cooper是个名人，也是患者，他曾经高度赞扬过动物研究的价值。由此可以推断他是支持动物研究的，正确答案是D。 -
第22题：
An Essential Scientific Process
All life on the earth depends upon green plants. Using sunlight, theplants produce their own food. Then animals feed upon the plants. They take inthe nutrients the plants have made sted. But that’s not all.Sunlight also helps a plant produce oxygen. Some of the oxygen is used by theplant, but a plant usually produces me oxygen than it uses. The excess oxygenis necessary f animals other ganisms to live.
The process of changing light into food oxygen is calledphotosynthesis. Besides light energy from the sun, plants also use water carbon dioxide. The water gets to the plant through its roots. The carbondioxide enters the leaves through tiny openings called stomata. The carbondioxide travels to chloplasts, special cells in the bodies of green plants.This is photosynthesis takes place. Chloplasts contain the chlophyllsthat give plants their green col. The chlophylls are the molecules thattrap light energy. The trapped light energy changes water carbon dioxide toproduce oxygen a simple sugar called glucose.
Carbon dioxide oxygen move into out of the stomata. Watervap also moves out of the stomata. Me than 90 percent of water a planttakes in through its roots escapes through the stomata. During the daytime, thestomata of most plants are open. This allows carbon dioxide to enter the leavesf photosynthesis. As night falls, carbon dioxide is not needed. The stomataof most plants close. Water loss stops.
If photosynthesis ceased, there would be little food other ganicmatter on the earth. Most ganisms would disappear. The earth’s atmospherewould no longer contain oxygen. Photosynthesis is essential f life on ourplanet.
词汇：
nutrient n.营养物
ganism n.生物体，有机体
carbon dioxide n.二氧化碳
chloplast n.叶绿体
molecule n.分子
vap n.水蒸气
oxygen n.氧气
photosynthesis n.光合作用
chlophyll n.叶绿素
glucose n.葡萄糖
cease v.停止
注释：
1.Then animals feed upon the plants.动物以植物为食。
练习：
4.This passage is primarily developed by
A.explaining a process.
B.telling a sty.
C.comparing contrasting.
D.convincing the reader of plants’ imptance.答案：A解析：4.A 文章先是介绍了进行光合作用所需的原料和组织，又介绍了光合作用的过程，因此整个逻辑应该是解释过程，而不是讲故事或比较对比。D项是“向读者说明植物的重要性”，这确实是文章的一个目的，但不是文章的组织方式。 -
第23题：
单选题According to the experts, the reversal of the Earth’s magnetic field would _____.Adestroy almost all the creatures on the Earth
Bcause some species extinctions on the Earth
Cnot be as disastrous as the previous one
Dcause no big trouble for man and animals
正确答案： A解析：
第三段最后一句：但是专家说这种影响不会造成大的灾难，尽管世界末日之称以及一些不明确的证据把物种灭绝与上一次地球磁场转移相提并论。