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问题 单项选择题

由于关系模式设计不当所引起的问题是( )。

A．数据冗余

B．数据被非法读取

C．数据被非法修改

D．发生死锁

答案

参考答案：A

解析： 如果关系模式设计不当，会引起数据冗余、更新异常、插入异常和删除异常。

填空题
阅读短文，从方框中选择适当的词并用其正确形式填空。方框中有两个词是多余的。
dirty with have always time they large want speak lesson first drop

     After a quick breakfast, I went into the lecture hall in a hurry. A famous teacher was    1    to the
students. He was holding up a $100 bill. Then he said to the three hundred students, "Who would like
this $1 00 bill?" The students put up    2    hands at once. Then he said, "I am going to give this $100
bill to one of you, but    3   , let me do this." He made the bill into a ball. Then he said. "Who    4    it
now?" The hands went back into the air, "Well," he said, "what if I do this?" and he    5    it on the floor
and stepped on it. He picked up the    6    bill and said. "Who still wants it?" Hands went back again into the air.
      "My friends,"  he said, "you have learned a valuable (有价值的)    7    today. No matter what I did
to the $100 bill! Many    8    in our life, we are dropped and stepped on. We feel as if we are worth nothing.
But remember, no matter what    9    happened to you, you will never lose your value: You are   10     
valuable to those people who love you. Your value doesn't come from what you do or whom you know,
but who you are."
1.______ 2.______ 3.______ 4.______ 5.______
6.______ 7.______ 8.______ 9.______ 10.______
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多项选择题

当代的公共政策评估所关注的是（）。

A.成本

B.效益

C.公平

D.效率
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