Little Tommy was doing very badly in math. His parents had tried everything tutors(家庭教师)，cards，special learning centers in short，everything they could think of. Finally they took Tommy to catholic (天主教的)school.

 The best way of learning a language is using it. The best way of learning English is talking in English as much as possible. Sometimes you’11 get your words mixed up and people will not understand you. Sometimes people will say things too quickly and you can’t understand them. But if you keep your sense of humor，you can always have a good laugh at the mistakes you make. Don’t be unhappy if people seem to be laughing at your mistakes. It’s better for people to laugh at your mistakes than to be angry with you，because they donrt understand what you are saying. The most important thing for learning English is “Don’t be afraid of making mistakes because everyone makes mistakes. ”The only thing that can stop you is the doubt that you carry in your mind.

Why will be water sink to the bottom of the tank when it is poured into the tank of gasoline?

()the fires can be put out with water.

According to paragraph 2，what will happen to the water if it is poured on the fire?

Gasoline fire should be put out .

From the passage，we can infer (推断)that().

  There are many ways of putting out a fire. You may have seen people put out burning cigarettes by stepping on them. Stepping on cigarettes shuts off the air and puts out the fire.

  Many fires are put out with water. Water cools the materials that are burning. It helps make the fire die out.

  Some of the water is changed into steam when it strikes the hot fire. The steam keeps air from the fire and helps put it out.Some fires can not be put out with water. Suppose a tank full of gasoline is on fire. Gasoline is lighter than water. If you poured water into the tank of gasoline，the water would sink to the bottom of the tank. The gasoline would float on top of the water on the fire and flow over the edge of the tank. Then the fire would spread.Gasoline fires should be put out with sand or with chemicals of some kind，such as that used in some fire extinguishers (灭火器).

  People often put out burning cigarettes by stepping on them.This is because ().

“hitting the books" means “()” in Chinese.

The last sentence in the passage shows that().

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