Even if you are a good high-jumper, you can jump only about seven feet off the ground. You cannot jump any higher because the earth pulls you hard. The pull of the earth is called gravity.
You can easily find out the pull of the earth. If you weigh yourself, you will know how much gravity is pulling you.
Since there is gravity, water runs down hill. When you throw a ball into the air, it falls back down. Because of gravity, you do not fall off the earth as it whirls (旋转) around.
Then, can we get away from the earth and go far out into space? Now you can do it, because spaceships have been invented. Then spaceship will go so fast that it can escape (逃出) the earth’s gravity and carry you into space.
1. In this passage, the word “gravity” means.
A. the pull of everything.
B. the force of attraction(吸引) among objects.
C. the force which attracts objects towards the centre of the earth
D. the force which attracts the earth towards the sun.
2. When you slip(滑) you always fall to the ground because
A. the earth always turns round. B. the earth has gravity
C. the earth’s gravity is greater than your weight. D. you are careless.
3. Gravity is strong that
A. it can throw a ball into the air. B. it makes you jump only seven feet.
C. it can let you fly away from the earth. D. it can keep everything on earth.
4. Because of gravity,
A. water flows everything. B. we can go everywhere by ship.
C. water always flows downwards. D. fish can live in water.
5. We can get away from the earth by spaceship because
A. the spaceship goes very fast. B. the earth can’t pull the spaceship.
C. the spaceship has a strong force. D. the spaceship can jump higher than other things.
参考答案:
1C 2 B 3 D 4 C 5 A
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