阅读理解。
Scientists are trying to make the deserts 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 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 places. Plants don't let the
hot sun make the earth even drier. Plants don't let the wind blow the dirt 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. Deserts _________. [ ]
A. get very little rain
B. never have any plants or animals in them
C. can all be turned into good land in the future
D. both A and C
2. Small green plants are very important to day places because ________. [ ]
A. they don't let the sun make the earth even drier
B. they don't let the wind blow the earth away
C. they hold the water
D. A, B and C
3. Land is becoming desert little by little because ________. [ ]
A. plants can't grow there
B. there's not enough rain
C. people are doing bad things to the earth.
D. scientists know little about desert
4. Which is the main idea of the first paragraph? [ ]
A. Scientists know how to change land 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 the desert, people can live there.
D. More and more places are becoming deserts all the time.
5. After reading this, we learn that ________. [ ]
A. plant can keep dry land from becoming desert.
B. it is good to get rid of (清除) the grass in the desert
C. all places without much rain will become deserts
D. it is better to grow crops on dry land than to grow grass
2H2O+O2↑ ；供给呼吸