问题 问答题

为了预防“非典”,小宇的妈妈买回一个消毒用的手执喷雾器,图中是手执喷雾器的结构示意图,请你写出这种喷雾器在工作过程中,应用到哪些物理知识?

答案

(1)手压压柄部分,压杆和出水管接触的部分为支点,构成一个杠杆;

(2)压杆下面有弹簧,按动压杆时,弹簧压缩形变,产生了弹力;

(3)按动压杆,活塞向右运动,导致进水管内气压减小,在大气压作用下把消毒药水压进进水管内;

(4)弹簧受到挤压后会把动能转化为弹性势能.

选择题
阅读理解

阅读理解。

                                                        How I Turned to Be Optimistic

     I began to grow up that winter night when my parents and I were returning from my aunt's house, and

my mother said that we might soon be leaving for America. We were on the bus then. I was crying, and some

people on the bus were turning around to look at me. I remember that I could not bear the thought of never

hearing again the radio program for school children to which I listened every morning.

     I do not remember myself crying for this reason again. In fact, I think I cried very little when I was saying

goodbye to my friends and relatives. When we were leaving I thought about all the places I was going to see

the strange and magical places I had known only from books and pictures. The country I was leaving never to

come back was hardly in my head then.

     The four years that followed taught me the importance of optimism, but the idea did not come to me at

once. For the first two years in New York I was really lost - having to study in three schools as a result of

family moves. I did not quite know what I was or what I should be. Mother remarried, and things became

even more complex for me. Some time passed before my stepfather and I got used to each other. I was often

sad, and saw no end to "the hard times".

     My responsibilities in the family increased a lot since I knew English better than everyone else at home. I

wrote letters, filled out forms, translated at interviews with Immigration officers, took my grandparents to the

doctor and translated there, and even discussed telephone bills with company representatives.

     From my experiences I have learned one important rule:almost all common troubles eventually go away!

Something good is certain to happen in the end when you do not give up, and just wait a little! I believe that my

life will turn out all right, even though it will not be that easy.

1. How did the author get to know America?[ ]

A. From her relatives.

B. From her mother.

C. From books and pictures.

D. From radio programs.

2. Upon leaving for America the author felt _____. [ ]

A. confused

B. excited

C. worried

D. amazed

3. For the first two years in New York, the author _____.[ ]

A. often lost her way

B. did not think about her future

C. studied in three different schools

D. got on well with her stepfather

4. What can we learn about the author from Paragraph 4? [ ]

A. She worked as a translator.

B. She attended a lot of job interviews.

C. She paid telephone bills for her family.

D. She helped her family with her English.

5. The author believes that _____. [ ]

A. her future will be free from troubles

B. it is difficult to learn to become patient

C. there are more good things than bad things

D. good things will happen if one keeps trying