看图回答问题。
1. -What can we do to keep our city clean?
- We can take the___________ to school.
2. -What can we do to keep the air clean?
- We can ___________.
3. -What can we do to keep our city clean?
- We can move some ___________ away from our city.
4. -What makes our city dirty?
- ___________ from cars makes the air dirty.
5. -What can we do to keep the river clean?
- We can put the rubbish in the ___________.
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