Is the sky blue? The sky has no colour. We know that there is air around the world. When planes fly，they need air to lift their wings(翅膀).Planes cannot fly very high because when they go higher，the air gets thinner. If we go up about l 200 kilometers from the earth，we find there is no air.

Perhaps we can answer some of our questions now. The sky is space. In this space there is

only the sun，the moon and all the stars.

根据短文内容选择正确答案:

1.What is the sky?(　)

A. It’s the clouds.　　　　　　　　　　    B. It's space.

C. It’s air.　　　　　　　　　　    D. It’s nothing.

2.They sky________.(　)

A. is blue　　　　　　　　　　    B. is white

C. is black　　　　　　　　　　    D. has no colour

3.A plane cannot fly very high because________.(　)

A. the air becomes thinner

B. the flying machine is not good

C. people Will be afraid if the planes fly too high

D. it is not necessary for planes to fly so high

4.If we go up about l 200 kilometers from the earth，we find________.(　)

A. there is more air　　　　　　　　　　    B. there is 1ess air

C. there is nothing but air　　　　　　　　　　    D. there is no air

5.In space there is________.(　)

A. nothing　　　　　　　　　　    B. air everywhere

C. everything　　　　　　　　　　    D. only the sun. the moon and all stars

Many people say that they have seen flying saucers（飞碟）in the sky.   31   can these things be ?

Some people think that they are spaceships from other planets. Doctors   32   that perhaps they are only a weakness of the eyes. It is possible that they are our own planes   33   very high. Or are they birds with the sun’s light on them?

But some people say that they have seen them   34  . They have seen beings（人）get off them and walk around. They have   35   to those beings, sometimes in English. People have   36   photos of flying saucers and of these beings. We have seen the photos, but sometimes the people had to take them in a   37  . Children have seen flying saucers, and even dogs have seen them. Perhaps we do not think that the   38   of children, or dogs are important. But school-teachers have   39   seen them and Air Force officers and   40   policemen. Must we not listen to these people?

1.A. How                           B. What             C. Which           D. Where

2.A. say                            B. prove             C. know            D. understand

3.A. rising                           B. flying             C. risen             D. flown

4.A. fly                              B. turn              C. land             D. move

5.A. flown                          B. gone           C. come             D. spoken

6.A. received                         B. bought            C. taken            D. sent

7.A. horse                            B. hurry              C. colour            D. way

8.A. opinions                       B. discussions        C. suggestions        D. needs

9.A. often                          B. hardly            C. also              D. still

10.A. yet                          B. even             C. so               D. then