题目内容
The surprising experiment I am about to describe proves that air is all aroud 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 Earth’s 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．Now for the experiment！
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
Metheod
1) Check that the egg 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 oxyen 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 pressure against the egg and then the egg is pushed into the bottle!The proves that air is all around and that it is pressing down on it．
53．When you do the experiment, why need you a person beside you?
A．You couldn’t place the egg on the bottle by yourself．
B．The egg needs to be shelled．
C．You need to use matches．
D．The bottle can’t sit firmly on the desk．
54．The purpose of doing this experiment is to prove ______．
A．air pressure is a wonderful force
B．water can push down your body when you swim underwater
C．the air pressure is not equalized around us
D．the earth is surrounded by a layer of air called the atmosphere
55．How did the egg put into the bottle？
A．The oxygen inside the bottle suckde the egg in．
B．It became solt without the shell．
C．The neck of the bottle was wide enough．
D．The outside air pressure forced it into the bottle．
56．The passage is ______．
A．an experiment report B．a scientific story
C．a research report D．an interesting novel
53-56 CADA
解析
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