- Trees on the hills can stop the rains from away the soil.
- The books are made _____ trees, and we can use trees in many different ways. [ ]
- More and more trees were cut down. _____, many animals are dying out. [ ]
- Planting apple trees is _____ interesting work, don’t you think so ?
- There are many trees on ______ side of the street.
- There are lots of trees on ______ sides of the street.
- Trees ____ fight air pollution．They are natural air conditioners．
- Trees provide food and shelter and make us ______ comfortable.
- Trees can prevent the wind _____ the earth away.
- The young trees should ______well as often as possible.