To extinguish (熄灭) different kinds of fires, several types of fire extinguishers have been invented. They must be ready for immediate use when fire breaks out. Most portable (手提式的) kinds operate for less than a minute, so they are useful only on small fires. The law requires（要求） ships, trains, buses and planes to carry extinguishers.
Since fuel, oxygen and heat must be present in order for fire to exist, one or more of these things must be removed or reduced to put out a fire. If the heat is reduced by cooling the material below a certain temperature, the fire goes out. The cooling method is the most mon way to put out a fire. Water is the best cooling material because it is low in cost and easy to get.
Another method of extinguishing fire is by cutting off the oxygen. This is usually done by covering the fire with sand, steam or some other things. A blanket may be used to cover a small fire.
A third method is called separation, which includes removing the fuel, or material easy to burn from a fire, so that it can find no fuel.
The method that is used to put out a fire depends on the type of fire. Fires have been grouped in three classes. Fires in wood, paper, cloth and the like are called Class A fires. These materials usually help keep the fire on. Such fires can be stopped most readily by cooling with water.
【小题1】If a fire breaks out on a bus, which of the following should be ready there for you to use?A．SandB．WaterC． A blanket.D．An extinguisher.【小题2】To cover a small piece of burning wood with a basin( 盆）in order to stop the fire is an example of .A．separating the fireB．reducing the heat C．removing the fuel D．cutting off the oxygen【小题3】In choosing how to put out a fire, we should first be clear about .A．when it breaks outB．how it es about C．what kind it isD．where it takes place【小题4】What would the author probably discuss in the paragraph that follows?A．Another class of firesB．Another type of extinguishersC．How fires break out.D．How fires can be prevented.D
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(答案→)D
解析：文章分析了不同的灭火原理和方法。
【小题1】细节题。根据第一段最后一行The law requires（要求） ships, trains, buses and planes to carry extinguishers.
【小题2】推理题。和第三段内容一样，这样做很明显是为了氧气，这样达到灭火的目的。
【小题3】细节题。根据文章最后一段第一句The method that is used to put out a fire depends on the type of fire.
【小题4】推理题。根据文章最后一段可知有三种火，刚刚在最后一段讲述了一种火，接下来应该是讲述另外一种火。