根据句意提示完成语篇。
A: Long long ago, there 【小题1】 many trees on Earth.
B: Yes, but now, we 【小题2】 wood to make tables, chairs and many other things.
A: We should not cut down too many trees. They help 【小题3】 the air clean.
B: You are right.
A: Can we use plastic to 【小题4】 bags or bottles?
B: No, we can’t.
A: Why?
B: 【小题5】 it is 【小题6】 for the Earth.
A: What can we do to 【小题7】 the Earth?
B: We shouldn’t use too 【小题8】 plastic bags or bottles.