单选题Which of the following is used to serve as an emergency backup line to troubleshoot a broadbandconnection on many routers?（）A DSLB POTSC VDSLD Smart jack
题目
单选题
Which of the following is used to serve as an emergency backup line to troubleshoot a broadbandconnection on many routers?（）
A
DSL
B
POTS
C
VDSL
D
Smart jack
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参考答案和解析
正确答案：
D
解析：
暂无解析