B. Listen to the dialogues and choose the best answer to each question you hear（根据听到的对话和问题，选出最恰当的答案）
() 6. A. Ocean plastic pollution. B. Air pollution in cities.
C. Noisy traffic. D. Cutting down forests.
() 7. A. Heavy rain. B. Industrial waste.
C. Fallen leaves. D. Hot weather.
() 8. A. Because it is cheaper. B. Because it takes more time.
C. Because it helps reduce air pollution. D. Because it is safer.
() 9. A. Water bottles. B. A plastic bag.
C. A box. D. A cloth bag.
() 10. A. It can carry 100 passengers. B. It produces only a little gas.
C. It has a fantastic look. C. It doesn't need a driver.

6. A 7. B 8. C 9. D 10. A

C. Listen to the long conversations and choose the best answer to each question you hear（根据听到的长对话,选出最恰当的答案）
Questions 11 to 13 are based on the following conversation.
() 11. What kind of pollution are the two speakers talking about?
A. Light pollution.
B. Noise pollution.
C. Air pollution.
D. Water pollution.
() 12. According to the boy, how does this pollution affect birds?
A. It makes them sing more.
B. It makes them lose direction.
C. It makes them eat less.
D. It makes them fly higher.
() 13. What will the government do next month?
A. Turn off all the street lamps.
B. Turn off half of the street lamps after midnight.
C. Build more warning signs.
D. Cut electricity for buildings.
Questions 14 to 16 are based on the following conversation.
() 14. How many trees will be planted by Eric’s class?
A. About two hundred.
B. More than a thousand.
C. About one hundred.
D. Fifty.
() 15. Why are local trees chosen?
A. Because they look nicer.
B. Because they are easy to grow and good for cleaning the air.
C. Because they are easy to get.
D. Because they are cheaper.
() 16. What should Lily bring to the activity?
A. Tools and small trees.
B. A camera and a notebook.
C. Gloves and a water bottle.
D. Food and drinks.

11. A 12. B 13. B 14. A 15. B 16. C