英語四級考試預測題聽力閱讀及寫作答案詳解

　　19. What is the discussion mainly about?

　　【解析】[C]對話一開始就談論人類骨骼的問題，女士說 But the fact is bones are made of dynamic living tissue that requires continuous maintenance and repair. 后面的對話都是針對這個話題展開的討論，可見整個對話討論的話題是骨頭的自我修復能力。

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

　　【解析】[C]男士解釋了第一組細胞的作用，第一組細胞生成一種化學物質(zhì)分解骨組織(This group of cells produces the chemical that actually breaks down the bone tissue…)，由此可見答案是They break down bone tissue.

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

　　【解析】[B]女士說這種特殊細胞作用于人類骨頭的過程相當復雜，事實上，連研究人類骨頭的科學家都不能完全了解這個過程。從這一句中可以知道：In fact, the scientists who study human bones don’t completely understand it yet. 所以答案即是這些科學家也不知道這些細胞如何工作。

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

　　【解析】[A]學習這些人類骨頭中的特殊細胞的重要目的是為了學習如何預防骨頭疾病。從男士的這一句話中可看出：That’ll prevent the disease from ever occurring. 這樣可以在疾病發(fā)生之前預防疾病，可見[A]符合題意。

　　Conversation Two

　　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:Y eah. 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.

　　Questions 23 to 25 are based on the conversation you have just heard.

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