听力原文:W:Hello? May I speak to Bill Johns? M:Hi,Amy.This is Bill. W:Oh,hi,Bill.You weren't in engineering class today,were you? M:No,I wasn't.(20)I have a flu.I was wondering if you could tell me what went on. W:I'm sorry that you are ill.Actually we had an interesting class。(19)Dr.Collin talked about a new type of fuel. M:Oh, yeah? Tell me more about it. W:Uh hum.It's called 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 says something about its exhausts being clear,that it doesn't release as much pollutants as diesel fuel.He mentioned something about DME being more efficient than other alternative fuels. M:When will it replace diesel fuel? W:Not for a while.It's not economical to mass produce.But it may happen in the future.After all,time will tell. M:Well,thanks for the information.(21)I guess I won't need to borrow your notes. W:(21)Well,maybe you should look at them.We are having a test next week.You have to prepare for it. 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:Thanks.Me too.Bye! (20)