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   Scientists are trying to make the deserts（沙漠）into good land（土地）again.They want to bring water to the desert，so people can live and grow food.They are learning a lot about the desert.But more and more land is becoming deserts.Scientists think that people make deserts.People are doing bad things.
   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.Some green plants and grass are very important to dry places.Plants don't let the hot sun make the earth very dry.Plants don't let the wind blow the dirt away.When a little rain falls，the plants hold the water.Without plants，the land can become a desert much more easily.
（1）Scientists want to bring

D

D

to the desert.
A．earth
B．rain
C．wind
D．water
（2）Because

B

B

do bad things，many places are becoming deserts.
A．a(chǎn)nimals
B．people
C．the sun
D．the wind
（3）Which sentence is NOT true？

B

B

A．Many places are becoming deserts.
B．Scientists ask people to live and grow food in the desert.
C．Scientists are learning a lot about the deserts.
D．Some places don't get much rain.
（4）The meaning of the underlined word"dirt"is"

B

B

".
A．地球
B．沙子
C．泥土
D．石子
（5）Why are green plants and grass helpful？

D

D

A．Because they can hold the water.
B．Because they can stop the wind from blowing the dirt away.
C．Because they can keep the earth wet.
D．A，B&C.