问题
填空题
| 用所给词的适当形式填空，其中有两项多余。 | |
| |
| There are a lot of trees around us. The trees can help to make the air 1 and cleaner. They can also help to 2 the weather. They provide(提供) humans with food, 3 , medicine and other things. Because of the trees, many animals can live 4 the earth. But people often cut trees down in large numbers. The forests are becoming much 5 than before, so we should protect them well. |
答案
1. fresher 2. control 3. rubber 4. on 5. smaller