66. Is＿possible to fly to the moon in a spaceship?

66. Is＿possible to fly to the moon in a spaceship?

Is＿possible to fly to the moon in a spaceship?

Is ________ possible to fly to the moon in a spaceship?

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阅读下列短文，从所给的四个选项中，选出最佳答案

　Gravity holds us so close to the earth's surface that nobody can jump more than a few feet into the air with the force of gravity pulling him down．It takes a powerful engine to keep an aeroplane up in the air．If you throw a ball upwards as hard as you can, you will notice that it travels in a curved（弯曲的）path before it comes back to the ground．If the earth had no gravity, the ball, instead of traveling in a curve, would move away in a straight line; in fact, it would never come back to the ground．If the earth were to lose its pull of gravity, we should all fly off it as it spins（旋转）round in space．The earth has a strong pull, but modern rockets going out into space are able to escape from the gravity, because they travel so quickly．With the ball thrown into the air, the height reached by the ball depends upon how hard it is thrown．The greater the starting speed, the higher the ball will go．If it could be thrown so that it travelled fast enough, the ball would escape into space and never come back．Nobody can throw a ball as fast as this, but powerful rocket engines can send spaceships away from the earth at such a speed that the earth's gravity is not able to pull them back．This is how we can now send rockets to the moon．

(1) Gravity holds us close to the earth's surface, and as a result, ______．

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A．we can lift ourselves no more than a few feet above the earth

B．nobody can jump a few feet into the air

C．no one will be pulled down

D．any one of us can jump as high as expected

(2) If there were no gravity, a ball thrown upwards would ______．　　　

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A．spin round in space

B．fall in a curved path

C．fly off into space

D．move towards the earth

(3) The ball thrown into the air would never come back to the ground ______．

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A．without a powerful push

B．if it were thrown upwards as hard as you can

C．should it travel in a curved path

D．were it not for gravity

(4) The height the ball will reach depends on ______．

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A．the escape speed

B．its starting speed

C．the limiting speed

D．its traveling speed

(5) What is it that makes it possible to put a spaceship into orbit（轨道）?

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A．The earth's gravity

B．A powerful engine

C．A strong pull

D．The powerful rocket engine