在“测定物质的密度”实验中，测量不规则铜块质量的器材应选用图中的______（选

阅读理解。

     How often one hears children wishing they were grown-ups and old people wishing they were young

again! Each age has its pleasures and its pains, and the happiest person is the one who enjoys what each

age gives him without wasting his time in useless regrets.

     Childhood is a time when there are few responsibilities to make life difficult. If a child has good

parents, he is fed, looked after and loved, whatever he may do. It is impossible that he will ever again in

his life be given so much without having to do anything in return. In addition, life is always presenting new

things to the child - things that have lost their interest for older people because they are too well-known.

But a child has his parents. He is not so free to do what he wishes to do; he is continually being told not

to do things or being punished for what he has done wrong.

     When the young man starts to earn his own living, he can no longer expect others to pay for his food,

his clothes, and his room, but has to work if he wants to live comfortably. If he spends most of his time

playing about in the way that he used to as a child, he will go hungry. And if he breaks the laws of society

as he used to break the laws of his parents, he may go to prison. If, however, he works hard, keeps out

of trouble and has good health, he can have the great happiness of building up for himself his own position

in society.

1. According to the second paragraph, the writer thinks that __.

A. life for a child is comparatively easy  

B. a child is always loved whatever he does

C. if much is given to a child, he must do something in return

D. only children are interested in life

2. After a child grows up, he _____.   

A. will have little time playing

B. has to be successful in finding a job

C. can still ask for help in time of trouble

D. should be able to take care of himself

3. Which of the following statements is NOT true according to the passage?

A. Those who can accept whatever happens in each age are happy.

B. Things are less interesting for older people.

C. Adults are free to do what they want to do.

D. Adults should no longer rely on others.

4. The underlined word "responsibilities" in the second paragraph means__________. 

A. duties      

B. jobs      

C. suggestions    

D. desires

5. The main idea of the passage is _________ .

A. life is not enjoyable since each age has some pains

B. young men can have the greatest happiness if they work hard

C. childhood is the most enjoyable time in one's life

D. one is the happiest if he can make good use of each age in his life

卢卡契认为现代艺术具有（）的倾向，而本杰明认为电影产生一种成人意料的（）效果。

层次分析法的特点是什么？关键步骤是什么？

M5卷烟机滤棒接收机终端排气装置用于（）。

A.改变滤棒输送管道内空气速度

B.提高滤棒输送量

C.减少滤棒输送量

D.保护滤棒不受磨损

水准仪望远镜的制动螺旋拧紧时，望远镜不能转动。