A、The high temperature required for its use. B、The high cost of materials used in its production. C、The lack of trained environm

W: Hi, Judy, mind if I sit down?
M: Not at all, Steven. How have you been?
W: Good. But I’m surprised to see you on the city bus. Your car is in the shop?
M: No. I’ve just been thinking a lot about the environment lately. The air will be a lot cleaner if we all use public transportation when we could.
W: I’m sure you are right. Though a diesel bus isn’t exactly pollution free.
M: True. But they’ll be running a lot cleaner soon. We were just talking about that in my environmental class.
W: What is the city going to do? Install pollution filters of some sort in all their buses?
M: 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 the engines more efficient.
W: How?
M: Well, there is a material called conium oxide. It’s a really good insulator. And a thin coat of it get sprayed on the certain part of the engine.
W: An insulator?
M: 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.
W: So a lot less unburned fuel comes out to pollute the air, right?
M: Yeah, and the bus will need less fuel. So with the savings on fuel cost, they say this will all pay for itself in just 6 months.
W: Sounds like people should all go out and get some of this stuff to spray their car engines.
M: 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 10,000 degrees and then, well, you get the idea.
It’s not something you or I will be able to do ourselves.
11. What is the conversation mainly about?
12. Why did the woman decide to take the city bus?
13. What is the conium oxide?
14. According to the woman, what may limit the use of conium oxide in cars?