补全对话.。 A: Can you tell us about the manatees, please? B: Sure, we are trying to save them. A: __ 1 __ B: Yes. There used to be many manatees, but now there aren't many of them. A: __ 2 __ B: At this point, there are only about 2,500 in the US. In 1972, it was discovered that they were endangered. Since then the government has passed laws to protect them. A: __ 3 __ B: Their favorite habitat is the water under the trees in mangrove swaps. A: __ 4 __ B: Some of the swamps have become polluted. Also, sometimes there isn't enough food for them. As you can see, they are large. The average manatee is about three meters long and weighs about 1,000 pounds. They need about 100 pounds of aquatic feed a day.. A: Aquatic feed? B: __ 5 __ A. That's underwater plants and vegetation. B. Where do they live? C. They are endangered. D. What do they eat? E. Are they endangered? F. Do you know how many there are?