听一段对话，回答第11—12小题。答题完毕，请等待“嘀”的信号，进入第一篇短文。
()11. What do wetlands act like according to the conversation?
A. The kidneys. B. The lungs. C. The heart.
()12. Why does the class want to start the activity?
A. To trap more carbon dioxide. B. To protect wetlands from pollution.
C. To learn about red-crowned cranes' homes.

听一段对话，回答第11—12小题。答题完毕，请等待“嘀”的信号，进入第一篇短文。
（）11. What do wetlands act like according to the conversation?
A. The kidneys.
B. The lungs.
C. The heart.
（）12. Why does the class want to start the activity?
A. To trap more carbon dioxide.
B. To protect wetlands from pollution.
C. To learn about red-crowned cranes' homes.

听第一篇短文，回答第13—15小题。请根据短文内容，选择正确答案，完成信息记录表。答题完毕，请等待“嘀”的信号，进入下一篇短文。
Facts about Deserts
Features Huge 13 differences between day and night.
Importance • Help keep nature anced.
• Home to some animals like 15 and lizards.
Problems Harmed by tons of 14 all year round.
()13. A. climate B. rain C. temperature
()14. A. camels B. lions C. birds
()15. A. bottles B. rubbish C. mud

听第二篇短文,回答第16—20小题。
()16. Why do we feel cooler in forests in summer?
A. Because trees produce cold air.
B. Because trees protect us from the hot sun.
C. Because trees keep cold winds away.
()17. What animals living in forests are mentioned?
A. Fish, dolphins and whales.
B. Lions, tigers and bears.
C. Foxes, eagles and rabbits.
()18. What do tree leaves do when it rains?
A. They grow much better.
B. They hold some water.
C. They all fall down.
()19. What helps new plants grow well in forests?
A. Fallen leaves.
B. Strong winds.
C. Cold air.
()20. What should we do for forests?
A. Cut down more trees.
B. Build houses there.
C. Keep them safe and clean.