阅读理解。

     If someone asks you "What color is the sky", I think your answer will be "blue". I'm afraid that you

are wrong. Because the sky has no color. 

     What's in the sky? Is the sky full of (充满) air? I'm sure that you have asked these questions. We all

know that there is air around the world. We can not live without air. Planes can't fly very high because

as we go higher, the air gets thinner (更稀薄). If we go far enough away the earth, we can find that there

is no air. The sky is space (太空). In the space there is nothing but the sun, the moon and the stars.

       People always want to know more about other worlds in space. They have looked at them through

telescopes (望远镜) and in this way they have known much. They know a lot about the moon now. but

they want to know more about space. I'm sure they will go farther and farther until they know all about it.

1. It's not really right _____. 

A. to answer questions about space  

B. to answer questions about the sky 

C. to say that the sky is blue        

D. to say that the sky has no color

2. _____ helps plane fly. 

A. The sky    

B. The air    

C. Space  

D. The sun

3. There is no air _____. 

A. around us    

B. around the eart  

C. in the sky

D. high enough in the sky

4. There is _____ in space. 

A. air                            

B. nothing 

C. nothing but the sun, the moon and the stars 

D. nothing or the sun, the moon and the stars

5. With telescopes people can know _____ in space. 

A. much    

B. nothing      

C. everything    

D. all