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问题 选择题

函数y=5x，x∈N+的值域是（　　）

A．R

B．N+

C．N

D．{5，52，53，54，…}

答案

解析：因为函数y=5x，x∈N+的定义域为正整数集N+，

所以当自变量x取1，2，3，4，…时，

其相应的函数值y依次是5，52，53，54，…．因此，

函数y=5x，x∈N+的值域是{5，52，53，54，…}．

故选D．

配伍题 B型题

哪类涂料不宜盛装液态食品（） |哪类涂料可溶出造成食品污染（）

A.溶剂挥于成膜涂料

B.高温液化涂料

C.加固化剂交联成膜树脂

D.氧化成膜树脂

E.高分子乳液涂料
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填空题

用下列词组的正确形式完成句子。

1  .Li Hong is such a girl who can _______her attention her study for a whole class.

2. Yesterday a robber, who refused to give in, was _______and fired to death by the policeman.

3.  An old worker was found__________a painting of Tang Dynasty.

4.  On May Day, _________shoppers entered the supermarket,

5. She is a talented musician ___________a photographer.

6. When the earthquake happened,_________, about 150 students were having PE lessons on the

playground.

7. She looked through_________information for the report.

8.  __________to reach the mountain summit,they made preparations for everything.

9.  Practical experience, ____________,can give us more useful knowledge.

10. It is dangerous to_______the union.
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