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   Scientists are trying to make the deserts (沙漠) into good land (土地). They want to _____ water to the deserts, so people can live and grow food. They are working hard. But there are more and more _____. Scientists think that _____ make deserts. They are doing _____ things to the earth.

Some places on the Earth don’t get very much rain. But they are good land. Because some green plants are growing there. The _____ are very important. They keep the earth wet. When it rains, the plants hold the water. With the help of the plants, the deserts can become land _____.