A、A fuel that burns cleanly. B、An oil additive that helps cool engines. C、A material from which filters are made. D、An insulatin

M: Hi, Diana. Mind if I sit down?
W: Not at all, Jack. How have you been?
M: Good. But I’m surprised to see you on the city bus. Your car in the shop?
W: No.(10)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. 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 gonna do? Install pollution filters of some sort on their 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 coniine oxide.(II)It’s a really good insulator. And a thick coat of it gets sprayed on certain part of the engine.
M: An insulator?
W: Well, yeah. Actually, 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, right?
W: Yeah, and the bus will need less fuel. So with the savings on fuel oil costs, they say this will all pay for itself in just six months.
M: Sounds like people should all go out and get some of this stuff to spray on their car engines.
W:(12)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,(12)you first have to heat it over 10,000 degrees and then, well, you get the idea. It’s not something you or I would be able to do ourselves.
Questions 9 to 12 are based on the conversation you have just heard.
9. What does the passage mainly talk about?
10. Why does the woman decide to take buses?
11. What is the coniine oxide according to the speaker?
12. What is the defect of coniine oxide according to the woman?