阅读理解。
Scientists(科学家) are trying to make the deserts (沙漠) into good land again . They want to bring
water to the deserts , so people can live and grow food . They are learning a lot about the deserts . But
more and more of the earth is becoming desert all the time . Scientists may not be able to change the
deserts . Scientists think that people make deserts . People are doing bad things to the earth .
Some places on the earth don’t get very much rain . But they still don’t become desert . This is because some green plants are growing there . Small green plants and grass are very helpful to dry places . Plants
don’t let the hot sun make the earth even drier . Plants don’t let the wind blow the earth away . When a
little bit of rain falls , the plants hold the water . Without plants , the land can become a desert much more
easily .
1. Why can the land become a desert ?
A. Some places don’t get very 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 .
2. Scientists ______ to make the deserts into good land again .
A. carry water
B. grow food
C. do nothing
D. study a lot
3. Which is not true ?
A. The land never stops becoming deserts .
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 .
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 .
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
O2(g ) = CO2( g ) △H＝─283.0 kJ / mol 。