听力原文：M: Hi Diana, mind if I sit down？W: Not at all, Jerry. How have you been？M: Good.

听力原文：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. Is your car in the shop？

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

M: You are right. The diesel bus isn't exactly pollution free.

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

M: What's the city going to do？ Install pollution filters in the buses？

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

M: How？

W: Well, there is a material called the coniine oxide. It's a really good insulator. And a thick coat of it gets sprayed on the certain part of the engine.

M: An insulator？

W: Yeah. Actually, what it does is to reflect back the heat of burning fuel. So the fuel will bum more completely.

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

W: Well, it's not really that easy. You first have to heat the material over 10,000 degrees and then, well, you get the idea. It's not something you or I can do ourselves.

(27)

A．How to produce pollution free bus.

B．How to prevent our environment from being polluted.

C．Whether to ride a passenger bus or a private car.

D．How to reduce the pollutants produced by bus.