问题 问答题

小娜同学在学习串联电路时,想通过实验证明:在串联电路中,开关串联在电路中的位置不同,但是开关对电路的控制作用相同.已经准备好的实验器材有:合适的电源一个,两个小灯泡L1和L2,一个开关S,导线若干.请你用这些器材跟小娜一起完成实验.

(1)画出实验电路图;

(2)写出主要操作步骤.

答案

(1)将两电器首尾相连即组成串联电路,实验电路图见图:

(2)主要操作步骤:

①按电路图连接电路,把开关S接在电路中的A点;并试触;

②闭合开关S,观察并在表格中记录电路通断情况(灯泡L1、L2发光情况);

③把开关S改接在电路中的B点,重复步骤②;

④把开关S改接在电路中的C点,重复步骤②.

阅读理解

阅读理解。

     There's a man in the habit of hitting me on the head with an umbrella. At first I couldn't stand it, now I'm

used to it. I don't know his name.

      I know he's average in appearance, wears a gray suit, and has a common face. I met him five years ago

one hot morning when I was sitting on a tree-shaded bench in Palermo Park, reading the paper. Suddenly I

felt something touch my head. It was the very same man who now, as I'm writing, keeps hitting me,

mechanically (机械地) and impassively, with an umbrella.

      On that occasion I turned around filled with anger. He just kept on hitting me. I asked him if he was crazy,

he didn't even seem to hear me. Then I threatened to call a policeman. Calmly, cool as a cucumber, he stuck

with his task. After a few moments of hesitation, and seeing that he was not about to change his attitude, I

stood up and hit him on the nose. The man fell down, but he immediately got back on his feet, obviously with

great effort, and without a word again began hitting me on the head with the umbrella. His nose was bleeding

and, at that moment, I felt sorry for him. I felt regret for having hit him so hard. After all, the man wasn't

exactly hitting me; he was merely tapping me lightly with his umbrella, not causing any pain at all. Of course,

those taps were extremely bothersome. As we all know, when a fly lands on your forehead, you don't feel any

pain; what you feel is annoyance. Well then, that umbrella was one huge fly that kept landing on my head time

after time.

      Convinced that I was dealing with a madman, I tried to escape. But the man followed me, wordlessly

continuing to hit me. So I began to run (I should point out that not many people run as fast as I do). He took

off after me, trying to land a blow. The man was out of breath so that I thought, if I continued to force him to

run at that speed, he would drop dead right then and there.

1. When the man began to strike the author with an umbrella, the author _____. [ ]

A. became angry

B. called the police

C. turned around and escaped

D. turned around and fought back

2. The author would most probably agree that the man was _____. [ ]

A. deaf

B. blind

C. dead

D. mad

3. The author felt sorry for the man because _____. [ ]

A. the man formed a bad habit of beating others

B. he hit the man so hard that his nose bled

C. the man couldn't catch up with him

D. there was a fly on the man's head

4. It can be learned from the passage that the man _____. [ ]

A. shouted loudly while hitting the author

B. wanted to tell the author something

C. ran after the author breathlessly

D. acted as if he were a fly

选择题