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A. It makes the air dirty. B. We should ride a bike more often. C. The air is clean and fresh there. D. It's from factories, cars and buses. E. I'm going to the Huangshan Mountain. |
Lily: Where are you going this winter holiday?
Mike：
Lily: That's a good idea.
Mike: Yes. Look at the smoke in the sky. Where is the smoke from?
Lily:
Mike：We need to do something to keep the air clean. What should we do?
Lily:
Mike：That's right.
