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 desert in time.
Why is more and more land becoming desert? 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 deserts. This is because
some green plants are growing there. Small green plants and grass are very important to dry (干的) places.
Plants don't let the hot sun make the earth even drier. Plants don't let the wind blow (吹) the dirt (土) away.
When a little rain falls, the plants hold the water. Without plants, the land can become a desert much more
easily.
1. Deserts ______.
[ ]
A. get very little rain
B. never have any plants or animals in them
C. can all be turned into good land soon
D. both A and C
2. Small green plants are very important to dry places because ______.
[ ]
A. they don't let the sun make the earth even drier
B. they hold water
C. they don't let the wind blow the earth away
D. all of the above
3. Land is becoming desert little by little (渐渐地) because ______.
[ ]
A. Plants can't grow there
B. There is not enough rain
C. People haven't done what scientists wish them to do
D. Scientists know little about the deserts
4. Which is the main idea of the first paragraph (段, 节)?
[ ]
A. Scientists know how to change desert into good land.
B. Land is becoming desert faster than scientists can change it back into good land.
C. If scientists can bring water to desert, people can live and grow food there.
D. More and more places are becoming deserts all the time.
5. After reading this, we learn that ______.
[ ]
A. plants can keep (阻止) dry land from becoming desert
B. it is good to get rid of (去除) the grass in the deserts
C. all places without much rain will become deserts
D. it is better to grow crops (农作物) on dry land than to grow grass