一、完形填空。
先通读短文，掌握其大意，然后从A、B、C、D四个选项中选出一个可以填入相应空白处的最佳选项。
The natural environment is very important.
Rainfall is one of the of the water cycle on the earth. The amount of rainfall make difference to the water cycle. Rainfall needs the plants they can make the clouds cool. The soil is for the growth of plants. And the plants food for animals. They can help to make the air clean and are also very important to the environment.
To have a healthy life, people fresh air and clean water. A healthy environment is good for people's . So people usually go to the mountains to have a good rest.
The environment is the key to the on the earth. Without it, there can be no life on the earth. In our solar system, there are other big planets. But there's no on them because they have no liquid water. Scientists are working on Mars to create life on . This shows the importance of the environment for life.
()1. A. activities B. steps
C. hopes D. results
()2. A. no B. any
C. a D. many
()3. A. because B. so
C. and D. but
()4. A. careful B. beautiful
C. useful D. colorful
()5. A. give B. help
C. provide D. want
()6. A. change B. need
C. protect D. collect
()7. A. work B. study
C. health D. chore
()8. A. life B. water
C. plant D. animal
()9. A. rock B. air
C. soil D. life
()10. A. it B. them
C. these D. one

1. B 由句意可知，降雨是水循环的众
多步骤之一。
2. C 由句意及常识可知，降雨的多少
对水循环有影响。
3. A 由上下文可知，降雨需要植物是
因为植物可以让云冷却下来。
4. C 由句意可知，土壤对植物生长是
有用的。
5. C provide sth. for sb. 意为“为某人
提供某物”，是固定结构。
6. B 由句意可知，为了拥有健康的生
活，人们需要清新的空气和干净
的水源。
7. C 由句意可知，健康的环境对人们
的健康是有益的。
8. A 由后句可知，环境是地球生命的
关键。没有环境，地球上就可能
不会有生命。
9. D 由下半句没有液态水可知，在太
阳系其他星球上没有生命。
10. A 由句意及本句前半部分的Mars
可知，此处应该用it指代火星。