在已知教学环境中，一名学生可以选择多门课程，一门课程可以被多名学生选择，这说明学生记

实验室中将氢气通入装有m g氧化铜的大试管，进行氧化铜的还原实验，当大部分固体变红时，停止加热，冷却后称得残留固体的质量为n g，共用去氢气w g，此时生成水的质量为（　　）

A．9wg

B．

9

8

(m-n)g

C．

8

9

(m-n)g

D．

9

40wg

完形填空。
Time spent in a bookshop can be enjoyable. __1   you go to a good shop, no assistant will come near to you and say, "Can I help you?" You __2    buy anything you don't want. You may try to find out. __3    the book you want is. But if you fail, the assistant will lead you there and then he will go away. It seems that he is __4   selling any books at all.      There is a story which tells us about a good shop. A medical student __5   a very useful book in the shop,    6    it was too expensive for him to buy. He couldn't get it from the library, either. So every afternoon, he went there to read _ 7    at a time. One day, however, he couldn't find __8 _ from its usual place and was leaving when he saw an assistant signing to him. To his surprise, the assistant pointed to the book __9   ,"1 put it there so as not to be sold out," said the assistant. Then he __10   the student to go on with his reading.
( )1. A. If           ( )2. A shouldn't   ( )3. A. what      ( )4. A surprised at   ( )5. A. bought       ( )6. A. but           ( )7. A. little       ( )8. A. the book     ( )9. A. in a bookshop ( )10. A. left	B. Because         B. needn't       B. which       B. not surprised at B. found       B. and               B. a little         B. the shop       B. in his hand   B. let	C. When         C. mustn't   C. where   C. interested in C. read         C. so           C. few           C. the assistant C. in a corner C. helped	D. But               D. can't             D. when               D. not interested in D. took               D. or                 D. a few             D. the shopkeeper     D. in his pocket     D. taught

余热处理钢筋属于（）级钢筋。

A.Ⅰ

B.Ⅱ

C.Ⅲ

D.Ⅳ

2003年公布的第四批国家非处方药目录(二)中有中成药( )

A．106种
B．160种
C．249种
D．361种
E．1330种

开关电源各整流模块器不宜工作在（）负载以下，如系统配置冗余较大可轮流关掉部分整流器以调整负荷比例。

A．10%

B．20%

C．30%

D．40%