1. The air in the city is very polluted.
2. How can we do to keep the environment clean?
3. Please listen to the lecture carefully.
4. I think the careless drivers should be fined for polluting.
5. She felt unhappy because of her bad result.
6. My uncle kindly provided a picnic lunch for us.
7. She has a keen interest in natural sciences.
8. I'm very worried because they use electricity to catch fish.
9. Gasoline fumes contribute to air pollution.
10. To my great disappointment, I didn't get the letter from her.