问题
单项选择题
在下列传输介质中，错误率最低的是________。
A．同轴电缆
B．光缆
C．微波
D．双绞线
答案
参考答案：B
解析：光纤电缆也称光缆，是网络传输介质中性能最好的一种。光纤信号衰减极小，它可以在 6-8km 的范 围内，在不使用中继器的情况下，实现高速率的数据传输；不受外界的电磁干扰与噪声影响，能在长距离、 高速率的传输中保持低误码率。
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在下列传输介质中，错误率最低的是________。
A．同轴电缆
B．光缆
C．微波
D．双绞线
参考答案：B
解析：光纤电缆也称光缆，是网络传输介质中性能最好的一种。光纤信号衰减极小，它可以在 6-8km 的范 围内，在不使用中继器的情况下，实现高速率的数据传输；不受外界的电磁干扰与噪声影响，能在长距离、 高速率的传输中保持低误码率。
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| Mr Black is a farmer. Last month he drove his car to a town and on the way his car knocked down a boy and hurt him. He sent the boy to a hospital at 1 .He paid a lot of money for that, but the boy's parents wanted _2 more money from him ,so they said their son could _ 3 lift his right arm 4 his head. M r Black's lawyer came and asked the boy 5 questions in the court. "Now my boy," he said."Mr Black's car knocked you 6 ?" "Yes, sir," said the boy. "And you can not lift your right arm over your head now?" " 7 ,sir," "Could you 8 us how high you can lift your right arm?" Slowly the boy lifted his right arm before his nose."Poor boy," said the lawyer. "And how high 9 you lift it before the accident?" "I could lift it very high."And the 10 went up high over his head. | ||||
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