7.In big cities , cars and buses have (污染) the air.
6.Some people have cut down too many tress . I t is a bad (举止) .
5.Trees can stop the wind from (吹)the earth away .
4. Many people don’t pay attention to (保护)nature .
3.If people spit something in public , they should be (处罚).
2.Each year people pour much (废物) into rivers , lakes and so on .
1. In some cities , vehicles (产生)too much noise .
10. I have been to an English (培训)school to improve my English .
第十七组
9.Poject Hope is a social (服务)program to help peopole.
8.The government (提供) homeless people with nice homes.