问题 填空题

在α粒子散射实验中,选用金箔是由于(    )

A.金具有很好的延展性,可以做成很薄的箔

B.金核不带电

C.金原子核质量大,被α粒子轰击后不易移动

D.金核半径大,易形成大角度散射

答案

ACD

α粒子散射实验中,选用金箔是因为金具有很好的延展性,可以做成很薄的箔,α粒子很容易穿过,A项正确.金原子核质量大,被α粒子轰击后不易移动,C项正确.金核半径大,易形成大角度散射,D项正确.

阅读理解

阅读理解。

      American schools’ beginning is in September after a long summer holiday. There are two terms in a

school year. The first term is from September to January, and the second is from February to June. Most American children begin to go to school when they are five years old. Most students are seventeen or

eighteen years old when they finish high school.

     High school students take only four or five subjects each term. They usually go to the same classes e

very day, and they have homework for every class. After class they do many interesting things.

After high school, many students go to college. They can go to a small one or a large one. They usually

have to give a lot of money. So many college students work after class to get the money for their studies.

1. How many terms are there in a school year in America ?

A. Four    

B. One    

C. Three    

D. Two

2. The first term is ______.

A. from February to June          

B. from January to September  

C. from June to February          

D. from September to January

3. When a child is ______ years old he or she can go to school.

A. five    

B. four    

C. seven    

D. six

4.How many subjects do the high school students take each term ?

A. As many as they like.    

B. Five.  

C. Four.    

D. Four or five.

5. Why do many college students have to work after class ?

A. Because some work is helpful to their studies.  

B. Because the teachers ask them to do so.

C. Because they like to work very much.  

D. Because they need to get money for their studies.

问答题