3. Biotechnology will help divide food into two groups: better food and healthier food. 　 T 　 F

2. People will be able to live in the new cities in the sea. 　 T 　 F

1. Cars using solar power or electricity will cause fewer accidents and less pollution. 　 T 　 F

5. Which is the best title(题目) for the passage? 　 A. The Desert Problem. 　 B. People Make Deserts. 　 C. Green Plants and Grass. 　 D. The Desert，the Tree and the Water.

参考答案

4. Why are green plants and grass helpful? 　 A. They can hold the water. 　 B. They can stop the wind from blowing the earth away. 　 C. They can keep the earth wet. 　 D. All the above are right.

3. Which is not true? 　 A. The land never stops becoming desert. 　 B. Scientists ask the people to live in the deserts and grow food there. 　 C. People do bad things to the earth. 　 D. Scientists may not be able to change the deserts.

2. Scientists ______ to make the deserts into good land again. 　 A. carry water　 B. grow food

　C. do nothing　　 D. study a lot

1. Why can the land become a desert? 　 A. Some places don't get much rain. 　 B. Plants don't let the hot sun make the earth even drier. 　 C. People don't keep the earth well. 　 D. Scientists haven't learnt enough about the deserts.