阅读下面短文，理解大意，从题中所给的A、B、C、D四个选项中选出一个最佳答案。
Ten, nine, eight, seven...zero—lift off. These words____like music to an astronomer's ears. As the countdown progresses, the rocket's engines____and give it the required push to tear through the atmosphere and____the earth's gravitation.
These rockets take astronauts and manmade satellites into____. The satellites are used for communication, weather monitoring and research. But how do satellites____up without falling down, you____ask?
Take a strong rope. Tie a small stone to one____to make a sling. Rotate the sling using one hand, you will____that the rope straightens out and becomes____as the sling rotates. As soon as you stop rotating, the rope slackens again. ____does the rope tighten on being rotated?
The answer to this question will____the answer to our query(疑问)how satellites remain in space without____down. When the sling is rotated, there are two____acting on the stone. The force of rotation, which tries to take the stone away from you and the force applied by your hand, which tries to____the stone towards you.
____you are rotating the sling, the two forces balance each other out and____the stone keeps going round and round. If you____the sling midway, the sling will fly off.
A satellite works in the same way. One of the two____forces acting on the satellite is the force of gravitation. ____force is that which is created by the rotation of the satellite____the earth. An orbiting satellite has these two forces balanced out so the satellite doesn't fall down to the earth.

A．look B．seen C．feel D．sound

A．hire B．fire C．break D．rush

A．escape B．reach C．increase D．decrease

A．universe B．world C．space D．stars

A．stay B．put C．keep D．take

A．should B．might C．dare D．ought

A．side B．top C．middle D．end

A．watch B．notice C．examine D．observe

A．loose B．strong C．tight D．short

A．What B．How C．Which D．Why

A．provide B．make C．receive D．accept

A．lying B．falling C．breaking D．turning

A．forces B．powers C．strengths D．energy

A．push B．drag C．throw D．pull

A．Though B．While C．Unless D．Until

A．however B．otherwise C．therefore D．instead

A．release B．tie C．fasten D．interrupt

A．familiar B．important C．opposite D．possible

A．The other B．Another C．Other D．Others

A．through B．into C．above D．around