问题 选择题

对于水平放置的平行板电容器,下列说法不正确的是(  )

A.将两极板平行错开,使正对面积减小,电容将减小

B.将两极板的间距加大,电容将增大

C.在下板的内表面上放置一面积和极板相等、厚度小于极板间距的陶瓷板,电容将增大

D.在下板的内表面上放置一面积和极板相等、厚度小于极板间距的铝板,电容将增大

答案

A、将两极板平行错开,使正对面积减小,根据公式C=

ɛs
4πkd
可知,C将变小.故A正确.

    B、将两极板的间距加大,d变大,C变小.故B错误.

    C、在下板的内表面上放置一面积和极板相等、厚度小于极板间距的陶瓷板,ɛ增大,C增大.故C正确.

    D、在下板的内表面上放置一面积和极板相等、厚度小于极板间距的铝板,板间距离减小.电容将增大.故D正确.

本题选不正确的,故选B.

阅读理解

One of the most popular items in the school newspaper is the advice column (专栏). Here are some of the questions asked and their answers.

Q: I’m always late for school. I try not to be late, but I can’t help it. Please advise me about what to do. Tommy.

A: You are probably late for school because you don’t really like school. My advice to you is to enjoy school more, and then you won’t be late so often.

Q: I find it difficult to make friends. What do you think I should do? Sara.

A: I can’t advise you until I know more about you. Your problem may be that you are shy. On the other hand, it may be the opposite. You may be bold(大胆的). Write and tell me more about yourself.

Q: I’m always at the bottom (末尾)of the class. What do you advise me to do? Molly.

A: I advise you to try to improve your grades in one subject at first. Next, try to improve your grades in another subject. If you do this, by the end of the year you should be quite a long way up from the bottom in all your subjects.

小题1:What is the main idea (主要意思) of this passage?

A.The town newspaper has an advice column.

B.Tommy wrote to the school newspaper to ask for advice.

C.Sara finds it difficult to make friends.

D.The advice column in the newspaper is very popular.小题2:What is Tommy’s problem?

A.He is always late for school.

B.He finds it difficult to make friends.

C.He is always at the bottom of the class.

D.He needs help with his homework.小题3:What does the adviser (建议者) want Sara to do?

A.Stop being so shy.

B.Stop being so bold.

C.Make more friends.

D.Give more information about herself.小题4:What does Molly want to do?

A.Make more friends.

B.Enjoy school more.

C.Stay at the bottom of her class.

D.Improve her exam results.小题5:By the end of the year, where should Molly be in all her subjects if she does as the adviser says?

A.At the bottom.

B.A little way up from the bottom.

C.Quite a long way up from the bottom.

D.At the top.

单项选择题