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.

　　23. What is the conversation mainly about?

　　【解析】[C]女士說為了環(huán)保應(yīng)該多乘坐公共交通設(shè)備，因此之后的話題便圍繞如何節(jié)能保護環(huán)境的問題展開。這段對話主要討論的是公共汽車的節(jié)能問題，討論了如何讓公共汽車燃料更有效的利用，因此[C]符合題意。

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

　　【解析】[B]對話開頭部分就交代了此題答案，那位女士說她不開自己的車而該乘公車是為了降低環(huán)境污染。從她提到的So I decided the air will be a lot cleaner if we all use public transportation when we could 即可得知。

　　25. What is the new material?

　　【解析】[D] 這種新的材料是在引擎部位噴灑的一種絕緣材料。從女士的話中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即可得出。這種材料的用途是將燃料燃燒的熱量反射回去，從而達到提高效率的結(jié)果。