问题
单项选择题
决定局域网特性的主要技术要素包括______、传输介质与介质访问控制方法。
A．所使用的协议
B．网络拓扑结构
C．数据传输环境
D．主机的时钟频率
答案
参考答案：B
解析：决定局域网特性的主要技术要素包括网络拓扑结构、传输介质与介质访问控制方法。其中最主要的是介质访问控制方法。
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决定局域网特性的主要技术要素包括______、传输介质与介质访问控制方法。
A．所使用的协议
B．网络拓扑结构
C．数据传输环境
D．主机的时钟频率
参考答案：B
解析：决定局域网特性的主要技术要素包括网络拓扑结构、传输介质与介质访问控制方法。其中最主要的是介质访问控制方法。
阅读下面短文，掌握其大意，然后从21～40各题所给的四个选项（A.B.C和D）中，选出最佳选项，并在答题纸上将该选项标号涂黑。 The subway train moved back and forth, its wheels producing more loud sounds than ever against the tracks. Outside the window was just the 21 cold of winter. The carriage was filled with frozen self-centered, bored 22 . Suddenly a little boy 23 his way in between grown-up legs. 24 his father stayed by the door, the boy sat next to the window, surrounded by 25 , half-awake adults. What a brave child, I thought. As the train entered a tunnel (隧洞), something totally 26 happened. The little boy slid down from his seat and put his 27 on my knee. For a moment, I thought that he wanted to go 28 me and returned to his father, so I moved a bit. But instead of moving on, the boy held his 29 up towards me. He wanted to tell me something, I thought. I 30 to listen to what he had to say. Wrong 31 ! He kissed me softly on the cheek. Then he returned to his 32 , settled down and cheerfully started looking out of the window. But I was 33. What happened? A kid kissing an unknown grown-up on the train? To my amazement, the kid 34 to kiss all my neighbors. Nervous and puzzled, we looked questioningly at his father. “He’s so happy to be 35 .” the father said. “He’s been very sick.” The train stopped and the father and son got down and 36 into the crowd. The doors closed. On my cheek I could still 37 the child’s kiss -- a kiss that had caused 38 soul-searching. How many grown-ups go around kissing each other 39 the joy of being alive? How many even give much thought to the privilege of living? What would happen 40 we all just started being ourselves? The little boy has given us a sweet but serious lesson: Don’t let yourself die before your heart  stops!
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