1．We’re trying to save the manatees.我们正在努力挽救海牛。

(1)try to do 努力做

　　 例如： 　　 I tried hard not to laugh.　　 我极力忍住不笑。

(2)try doing 试做(可达到目的的方法)

　　 例如： 　　 If the car won’t start，try pushing it.　 如果这车发动不了，试着推一推它。

11. Some of the swamps have become polluted.

一些沼泽地已经受到污染。(现在完成时)

10. In 1972，it was discovered that they were endangered.

　　　　　　 1972年发现海牛濒临灭绝。(被动语态)

9. There used to be a lot of manatees. 过去有许多海牛。(一般过去时)

8. Manatees eat about 100 pounds of food a day.

海牛每天要吃100磅左右的食物。(一般现在时)

7. We’re trying to save the manatees.

我们正在尽力挽救海牛。(现在进行时)

6. I feel that…我觉得…

5. I believe that…我相信…

4. I think that…我认为…

3. I agree / disagree with you. 我同意/不同意你的意见。