1. What laws do we need to protect the __________ from any kind of pollution.
2. Cars are one of the sources of air __________.
3. I want to tell my classmates about water pollution but I’m afraid to _________ in front of
the class.
4. Please don’t throw garbage anywhere. Please ________ those trash and put it in
the trash bin.
5. Many factories can _______ the air more than others.