What’s the conversation mainly about?

W:Hi, Bill. You weren’t in engineering class today, were you?
M:Hi, Amy. I have the flu. I was wondering if you could tell me what went on.
W:Actually we had an interesting class. Dr.Collin talked about a new type of fuel.
M:Oh, yeah?
W:Uh-hum. It’s called dimethyl ether or DME.
M:Oh, I remember reading something about DME. It’s mostly used in spray cans, right?
W:Right.DME doesn’t destroy the ozone, so it’s been environmentally friendly.
M:But doesn’t DME pollute the air if it’s burned in an engine?
W:Dr.Collin said something about its exhausts being clear, that it doesn’t release as many pollutants asdiesel fuel. And he mentioned something about DME being more efficient than other alternative fuels.
M:So when will it replace diesel fuel?
W:Not for a while.It’s not economical to mass-produce.
M:Well, thanks for the information. I guess I won’t need to borrow your notes.
W:Well, maybe you should look at them. We are having a test next week.
M:Okay,could you give them to Mike Andrews? I think he is in your psychology class.He is my roommate.
W:Sure. I hope you’re feeling better soon.
M:Thank you.