问题 单项选择题

对100Mbps的传输速率来讲,若采用曼彻斯特编码方式,则要求需要______MHz频率的器件实现。

A.100

B.125

C.150

D.200

答案

参考答案:D

解析:曼彻斯特编码的波特率是数据速率的2倍,当数据传输速率为100Mbps时,需要200MHz的脉冲。

完形填空

完形填空。

     Last Sunday I took my son to the zoo  1  the morning. I wanted my son  2   more about
animals. We  3   the No. 8 bus to the zoo.
     First we went to see the fishes and the birds. My son was very   4 . And he asked me a lot
of questions. "Don't always ask  5 . Please use your head." I told the boy.
    After we left the birds, my son  6  me that he wanted to have a rest. I looked  7   and
found a long chair under a tree. When we came to the chair, I saw a card  8   it. It said, "Don't
take the seat. The paint is wet."
    We had to see some monkeys, foxes, elephants. Then we saw some tigers and leopards.
    "Dad," my son said to me, " 9  I tell you a secret?" "Of course. What is it?"
    "I know where the spots of the leopards come from," said my son. "They come from the  10  ."
    "Why?" "Please look at the paint of the cage. It is wet now."
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选择题