2．　　 You mustn’t t___ the horse to the tree.

1．　　 He plays football so w___.

Light travels very fast. I t moves _1__300,000 kilometres a_2__. Light_3__us from the moon in less than a second and a half. The moon is about 382,000 kilometres _4__.

Light from the sun reaches us in 8.5 minutes. The sun is about 147,640,000 kilometres from the earth..

The other stars are farther away than the sun. Light from the nearest_5__ reaches us in about four years. When you look at a star, you do not __6_ its present condition (目前状况)。You see it as it _7__ to be. Light from some stars_8__ hundreds of years to reach us. We never see a star as it is _9__. We see it as it was long ago, perhaps hundreds or thousands of years ago.

Astronomers (天文学家) watch stars _10__ big telescopes (望远镜)。With these telescopes astronomers can see stars and other things very far away.

1. A. on　 B. at　 C. with　 D. by

2.A. minute　 B. hour　 C. second　 D. day

3.A. reaches　 B. gets　 C. arrives　 D. comes

4.A. High　 B. far　 C. long　 D. away

5.A. star　 B. moon　 C. sun　 D. earth

6. A. look at　 B. see　 C. touch　 D. reach

7. A. use　 B. used　 C. is used　 D. using

8. A. takes　 B. take　 C. spends D. spend

9. A. before　 B. after　 C. now　 D. future

!0. A. in　 B. through　 C. into　 D. onto

20.___the Great Green Wall, the rich farmland in the south has been saved.

　A. Thanks for　 B. Thanks to　 C. Because　 D. Since

19.In___ time , those mountains will be covered with trees.

A. few years　 B. a few year’s　 C. a few year　 D. a few years’

18.In the last ten years, we___ millions of trees on the mountains,

A. will plant　 B. have planted　 C. are planted　 D. are planting

17.I have a lot of work___.

A. to do　 B. do　 C. done　 D. to be done

16.The rain stopped us___ out.

A. to go　 B. for going　 C. from going　 D. of going