问题补充：
The surprising experiment I am about to describe proves that air is all around you and that it proves down upon you．Air pressure is a wonderful force．When you swim underwater, you can feel water push down your body．The air all around you does the same．However, your body is so used to it that you do not notice this．The pressure is caused by a layer of air called the atmosphere．This layer surrounds the Earth, extending to about five kilometers above the Earths surface．
The following experiment is an easy one that you can do at home．But make sure that you are supervised, because you will need to use matches．
What you need
·A hard-boiled egg without the shell
·A bottle with a neck slightly smaller than the egg
·A piece of paper
·A match
Method
1）Check that the paper will sit firmly on the neck of the bottle．
2）Tear the paper into strips and put the strips into the bottle．
3）Light the paper by dropping a burning match into the bottle．
4）Quickly sit the egg on the neck of the bottle．
Result
Astonishingly, the egg will be sucked into the bottle．Your friends will be amazed when you show them the experiment．But be careful when you handle matches．
Why it happened
As the paper burns, it needs oxygen and uses up the oxygen （air）in the bottle．The egg acts as a seal in the neck of the bottle, so no more air can get inside．This reduces the air pressure inside the bottle．The air pressure must equalize, so more air from outside must enter the bottle．The outside air presses against the egg and then the egg is pushed into the bottle! That proves that air is all around and that it is pressing down on it．
【小题1】Why is there the need to take care when you are doing the experiment?A．The bottle could break．B．You need to light the paper with a match．C．The egg needs to be shelled．D．The egg has to be perfectly placed on the neck of the bottle．【小题2】In the experiment, the burning inside the bottle can．A．equalize the air pressure inside and outsideB．make a seal in the neck of the bottleC．finish up the oxygen inside the bottleD．produce more oxygen inside the bottle【小题3】How did the egg put into the bottle?A．The oxygen inside the bottle sucked the egg in．[来源:学。科。网]B．It became salt without the shell．C．The neck of the bottle was wide enough．D．The outside air pressure forced it into the bottle．【小题4】The experiment is carried out to prove ．A．water pushes on your body when you swim underwaterB．the earth is surrounded by a layer of air called the atmosphereC．the pressure of air around us has a powerful forceD．the air pressure is not equalized around usB
答案：
(答案→)B
解析：
【小题1】细节理解题。从Result下面的But be careful when you handle matches可以作出判断。
【小题2】细节理解题，从Why it happened下面的As the paper burns, it needs oxygen and uses up the oxygen （air）in the bottle可以判断瓶子内部的氧气被消耗殆尽。
【小题3】细节理解题。从Why it happened下面的The outside air presses against the egg and then the egg is pushed into the bottle!可以作出判断。
【小题4】主旨大意题，文章第一句话The surprising experiment I am about to describe proves that air is all around you and that it proves down upon you．开门见山，提出了写作的目的。
