W: Very good. This is a very complex process. In fact, the scientists who study human bones don’t completely understand it yet. They are still trying to find out how it all actually works. Specifically, because sometimes after the first group of cells leaves a hole in the bone tissue, for some reason, the second group doesn’t completely fill in the hole. And this can cause real problems. It can actually lead to a disease in which the bone becomes weak and is easily broken.

　　M: Ok, I get it. So if the scientists can figure out what makes the specialized cells work, maybe they can find a way to make sure the second group of cells completely fills the hole in the bone tissue every time. That’ll prevent the disease from ever occurring.

　　19. What is the discussion mainly about?

　　20. What is the function of the first group of specialized cells discussed in the talk?

　　21. What does the professor say about scientists who study the specialized cells in human bones?

　　22.According to the student, what is one important purpose of studying specialized cells in human bones?

　　Conversation 2

　　答案：CBD

　　原文：

　　M: Hi Diana, mind if I sit down?

　　W: Not at all, Jerry. How have you been?

　　M: Good. But I’m surprised to see you on the city bus. Your car in the shop?

　　W: No. I’ve just been thinking a lot about the environment lately. So I decided the air will be a lot cleaner if we all use public transportation when we could.

　　M: I’m sure you are right. The diesel bus isn’t exactly pollution free.

　　W: True. They’ll be running a lot cleaner soon. We were just talking about that in my environmental engineering class.

　　M: What could the city do? Install pollution filters in all their buses?

　　W: They could, but those filters make the engines work harder and really cut down on the fuel efficiency. Instead they found a way to make their engines more efficient.

　　M: How?

　　W: Well, there is a material that’s a really good insulator. And a thin coat of it gets sprayed on the certain part of the engine.

　　M: An insulator?

　　W: Yeah. What it does is reflect back the heat of burning fuel. So the fuel will burn much hotter and burn up more completely.

　　M: So a lot less unburned fuel comes out to pollute the air.

　　W: And the bus will need less fuel. So with the saving on fuel cost, they say this will all pay for itself in just six months.

　　M: Sounds like people should all go out and get some this stuff to spray their car engines.

　　W: Well, it’s not really that easy. You see, normally, the materials are fine powder. To melt it so you can spray a coat of it on the engine parts, you first have to heat it over 10000 degrees and then, well, you get the idea. It’s not something you or I will be able to do ourselves.

　　23. What is the conversation mainly about?

　　24. Why did the woman decide to ride the city bus?

　　25. What is the new material?

　　三、选词填空

　　1. I) 2. B) 3. D) 4. E) 5. F) 6. G) 7. K) 8. M) 9. N) 10. O)

　　四、改错

　　1. like → as

　　2. Those → Some

　　3. or → and

　　4. called as→ call

　　5. Such → Such an

　　6. that → which

　　7. essential → nonessential or +not

　　8. visits → visits to

　　9. basic → based

　　10. economist → economist's

　　五、短问

　　1. It was a basis for the academy founded by Franklin.

　　2. Latin and Greek

　　3. to learn moral and ethical principles

　　4. practical

　　5. practical skills

　　六、翻译

　　1. mainly due to stress and tension in their work

　　2. more than two and a half million families have been lifted out of poverty

　　3. All the board members except the Chairman voted for my proposal

　　4. providing new growth opportunities for China's foreign and domestic trade

　　5. This is especially true of developed countries

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