下列不属于计算机网络体系结构特点的是( )。
A．是抽象的功能定义
B．是以高度结构化的方式设计的
C．是分层结构，是网络各层及其协议的集合
D．在分层结构中，上层必须知道下层是怎样实现的
参考答案：D
解析： ①计算机网络层次结构模型和各层协议的集合定义为计算机网络体系结构：②网络体系结构是对计算机完成功能的精确的定义，而这些功能是用什么样的软件和硬件实现的，则是具体的实现问题。体系结构是抽象的，而实现是具体的，是能够运行的一些硬件和软件；③计算机网络中各层之间相互独立。高层并不需要知道底层是如何实现的，仅需要知道该层通过层间的接口所提供的服务。所以答案为D)。
完形填空。(每小题 2分，共 20分) 根据短文内容，从 A、B、C、D 四个选项中选出一个最佳答案，并把答题卡上对应题目的答案 标号涂黑。 Do you often communicate with your parents? Some parents are always comparing their 41 with themselves when they were young or with other people when they were children. "When I was your age," a father said to his sixteen-year-old son one day, "I was at the top of my class every year. And I 42 what I wanted to do when I left school. I had goals (目标). You are always at the bottom (最后) of your class 43 you have no goals." The man’s son said nothing. He had already heard this from his father many times. "And when your mother was your age, " the young man’s father 44 , " she had a good job and she 45 lots of money. You don’t even have a part-time job .You earn nothing. " The man’s son still said nothing. He had heard this before, too. " And when your 46 brother was your age, "the young man’s father said, "he studied hard. But you just waste your time." And the man’s son still said nothing. Finally, the young man’s father said, "And when Abraham Lincoln was your age, he worked all day and studied at night." This time the son 47 stay silent. " And when Abraham Lincoln was your age, father," he said, "He was the President of 48 United States. 49 are you?" His father had no answer 50 this. Are your parents always comparing you with others? And what’s your reply? Do you have a better way to communicate with each other?
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