M: An insulator?
W:Y eah. 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.
W: And the bus will need less fuel. So with the saving on fuel cost, they say this will all pay for itself in just six months.
M: Sounds like people should all go out and get some this stuff to spray their car engines.
W: Well, its 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 10000 degrees and then, well, you get the idea. Its not something you or I will be able to do ourselves.
Questions 23 to 25 are based on the conversation you have just heard.
Passage Two
People dreams four to six times a night. They dream while they are in the REM stage of sleep, which means rapid eye movement stage in ones sleep. Sleepers go into the REM stage about every 90 minutes. The first dream of the night may last about ten minutes. Each dream gets a little longer. The last dream of the night may be an hour long.
People need their dreams. Younger children spend more time dreaming. Babies spend almost half of their sleep in the REM stage.
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