题目内容：

阅读下面四篇材料，然后从A、B、C、D四个选项中选出最佳选项。

I don’t have too many memories of my father because he was so sick in the last years of his life. But there are some that I am often reminded of and which may have developed my love of science.

When I was small， I was somewhat afraid of lightning and thunder（雷）. My father explained it. The explanation was in words that a child could understand but was basically correct. I gained a better understanding and learnt something from him.

What he said was that there was electricity in the clouds and it traveled to the ground like a spark(火花). When it traveled through the air， it made the air so hot that it burned. Then there was nothing where the air had been and the air all around rushed in to fill the space. Saying this， he clapped his hands together very loudly， pretending to be the air rushing in， and said that makes the thunder. When I hear thunder， I can still hear that clap clearly.

He also explained why a cloudy winter night was warmer than a clear one. When there were clouds， they were like blankets(毛毯) which kept the earth and us warm. He said that if there were no clouds， we had no blankets and were exposed to the universe. Our warmth was going to heat the whole universe. Even today， I still feel on the edge of space on a very clear night.

I am sure there were many other lessons that I took but no longer remember most of them now. What I did learn， in general， was that there were explanations and that the more I understood them， the more comfortable the world was to live in. I was not taught that there were mysteries but that there was understanding if you looked for it. This may be why I have always taken an interest in science.

1. The writer’s father explained that there was thunder because       and made it.

A. his hands clapped loudly      

B. rushing air filled the space

C. electricity traveled through the air 

D. thick clouds knocked into each other  

2.The underlined word“exposed”in paragraph 4 means        .

A. close         B. cold         C. covered         D. open

3.What did the writer think of his father’s explanation according to the passage?

A. Silly and strange       

B. Scientific and difficult

C. Simple but scary         

D. Vivid and understandable

4.We can know from the passage that        .

A. the writer is smart enough to learn much

B. the writer has a good memory about learning

C. the writer has a good understanding of things in life

D. the writer was taught there were many secret things in the world