听录音，填入所缺的单词。

All the know that Earth is our home. In fact, our Earth is in . There are so many serious problems(严重的问题) about it. Air pollution (污染)is one of them. from cars and factories makes the air . The sky isn't any more. People cut down trees for , but that's for the air, because trees help keep the air clean. Water pollution is the other one of them. Water is so and important for us. There is no clean water, there is no life in the future. pollution is another serious problem. People use too much plastic.

What can we do to the Earth? I'm going to make some kinds of posters to get more people to think about the world around us. How about you?