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问题 单项选择题

以下关于网桥的描述中，错误的是（）。

A．网桥工作在数据链路层

B．网桥最重要的维护工作是构建和维护MAC地址表

C．使用网桥实现数据链路层的互联时，互联网络的数据链路层和物理层协议必须相同

D．目前，网桥仍需要解决同种标准中不同传输速率的局域网在MAC层互联的问题

答案

参考答案：C

解析：

在使用网桥实现数据链路层的互联时，允许互联网络的数据链路层与物理层协议不同。

完形填空

根据所给的首字母填写单词

This story took place more than 2,000 years ago. There was a young farmer. His family had been farmers for generations（世代）. Year a小题1: year and generation after generation,farmers used to plant in spring and h小题2:  in autumn, beginning to work at sunrise and finishing work at s 小题3: . In good harvest years,they could only have enough food to eat and enough clothing to w小题4:   .If there was a famine（饥荒） due to(由于) crop failure, they had to go hungry. This young farmer wanted to i小题5:  his life. Being lazy and cowardly over everything,he often dreamed of having unexpected result. A strange thing t小题6:  place at last. One day in late autumn, two groups of people were hunting nearby while he was ploughing in the field. As shoutings were rising one after a小题7:   ,scared hares（野兔） were running desperately. Suddenly,a hare clashed(撞) itself against the stump of a dead tree in his field and died. That day, he ate his fill. From that day on,he no longer went in for farming a小题8:  . From morning till n小题9:  ,he stayed by that stump, waiting for miracles(奇迹) to take place again.

Later people often use the set phrase "staying by a stump waiting for more hares to come and clash t 小题10:    against it to show trusting to chance and wind falls or dreaming to reap（收获） without planting. It is also used to show adhering（依附，坚持） to narrow experiences and not being able to be flexible（灵活的）.
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填空题

停车后盘车的目的是（）防止单向受力。
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