Antifreeze is a liquid(液体) that is added to water to keep it from freezing． When water freezes and turns to ice，it expands(膨胀)．The force of water expanding is so great that it will break the hardest metal．Water is used in car engines(发动机) to keep them cool while they run，and if this water is allowed to freeze in winter it can break the iron block of the engine．That is why antifreeze is necessary．
Water freezes at 0℃；the usual kind of antifreeze will not freeze until the temperature is－40℃．A mixture(混合物) of five parts of water and four parts of antifreeze will prevent freezing at－18℃；four parts of water and five parts of antifreeze reduce this to －22℃．
Alcohol is a kind of good antifreeze，but when the air is running it bees hot and the alcohol boils away，so it must be changed very often．Most people use antifreeze that does not boil away when the engine is running．There are several chemicals that do this．One of the most popular is called ethylene glycol．
【小题1】people use to keep car engines cool．A．antifreezeB．waterC．alcoholD．ethylene glycol.【小题2】The usual kind of antifreeze freezes at ．A．0℃B．－18℃C．－22℃D．－40℃【小题3】We use antifreeze in order to ．A．keep alcohol in waterB．stop ice from being waterC．make the freezing point of water lowerD．raise the freezing point of water【小题4】Besides alcohol， is another kind of popular antifreeze．A．waterB．ethylene glycolC．any chemicalD．any mixture【小题5】The text is written to ．A．tell us what antifreeze isB．make people buy antifreezeC．tell us that cars need antifreezeD．show us how to protect car enginesB
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(答案→)B
解析：防冻液是一种液体，加入到水中可防止水结冰。当水结成冰的时候，它会膨胀。水膨胀的力很大，可以把最硬的金属涨破。这就是为什么在冬天汽车的引擎中加防冻液的原因。
【小题1】细节理解题。根据文章第一段三，四两行可知。
【小题2】细节理解题。根据文章第一段倒数第三行，四行可知。
【小题3】细节理解题。根据文章第一段倒数一二两行可知。
【小题4】细节理解题。根据文章最后一段最后一句可知。
【小题5】主旨大意题。这篇文章主要讲述的是什么是防冻液以及为什么会使用防冻液。