问题 选择题

关于电阻,下面说法正确的是(  )

A.铁导线的电阻不一定比铜导线的电阻大

B.细导线的电阻一定比粗导线的电阻大

C.半导体材料也可以做成输电的导线

D.不通电时导体就没有电阻

答案

A、不确定导线的长度以及横截面积,因此无法比较铁导线和铜导线电阻的大小,所以铁导线的电阻不一定比铜导线的电阻大,故A正确;

B、不确定导线材料和长度,因此无法进行比较粗导线和细导线的电阻大小,故B错误;

C、为了减小电能的损耗,用来做导线的都是电阻率较小的材料,所以半导体材料不可以做成输电的导线,故C错误;

D、电阻是导体的一种特性,和导体中有没有电流无关,故D错误.

故选A.

阅读理解

Read and choose. (选择正确的答案) 

     Bob is a middle school student. He studies in a middle school in the east suburbs (郊区) of California.

Bob goes to school from Monday to Friday. On weekdays, he always gets up at 7:00 o'clock, then he

has breakfast. He usually has a cup of milk, a piece of bread and two fried eggs for his breakfast. At

about 8 : 00 0'clock, he gets into his father's car and his dad drives it down the road towards his school.

Classes begin at 8 :30 and at 12 :30, he goes to the school canteen for lunch. In the afternoon,  when

classes are over,  Bob usually plays basketball with his classmates. Sometimes he also goes to the school

library to do some reading. In the evening, Bob may either watch an interesting TV program or do some

Internet surfing(冲浪). He goes to bed at 10 :00. His school days are busy, but he always enjoys them

very much.

1. Where does Bob live?          

A. He lives in a school.

B. He lives in California.

C. He lives in China.

2. How many days does Bob go to school in a week?              

A. Seven days.          

B. Six days.          

C. Five days.

3. Does Bob go to school by bus?           

A. No, he doesn't. His father drives him to school.

B. Yes, he does.

C. No, he doesn't. He goes to school by bike.

4. What does Bob do after classes?              

A. He goes home.

B. He plays basketball everyday.

C. He usually plays basketball and he also goes to the library.

5. Does Bob like his schooldays?              

A. Yes, he does.

B. No, he doesn't.

C. Just so-so.

6. What's the Chinese meaning of the word "canteen" ?           

A. 搡场                

B. 餐厅            

C. 图书馆

单项选择题