在下面对话的空白处填入适当的话语(话语可以是句子、短语或词)，使对话完整。
A: Hey, Ginny. What do you call those big, gray things in the water?
B: 1______.
A: What?
B: Manatees. They're very gentle and very shy.
A: 2______?
B: They're usually about 10 feet long and they weigh about 1000 pounds.
A: How much do they need everyday?
B: They need about 1 00 pounds of aquatic food a day.
A: 3______?
B: It is underwater plants and vegetation (植被).
A: That's what they eat?
B: Yes. it is.
A: 4______?
B: Yes, they are endangered (陷入困境). But, we're trying to save them.
A: Wait a moment. Why are they endangered?
B: 5______.
A: Where do they live?
B: They live in the swamps (沼泽). 6______.They are endangered also because there sometimes
isn't enough food for all of them.
A: 7______. There used to be a lot of manatees, but now there aren't very many ofthem left, I think.
B: Yes, 8______. At this point, there are only about 2,500 in the U.S.
A: 9______?
B: Since 1927 laws have been passed to protect them.
A: Thank you for your information.
B: 10______.