Scientistshavealwayswantedtoknowmoreabouttheotherworlds...

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Scientists have always wanted to know more about the other worlds in space. They have looked at them 1 the telescope and 2 this way they have found out 3 . They know, for example, many facts about the moon.

The moon is about 384,000 kilometers 4 the earth . A plane can not fly to the moon because there isn’t enough air. But a rocket can fly even when there is no air .

“How does a rocket fly ?” If you want to know, get a balloon and 5 blow it up 6 it is quite big. Do not 7 the neck of the balloon. Let it go 8 and see 9 happens. The balloon 10 through the air very quickly. The air inside the balloon 11 out. It rushes out through the 12 balloon and this pushes the balloon through the air. It does not need wings 13 .

This is 14 a rocket 15 . It is not made of rubber like a balloon, of course . It is made of metal. The metal 16 not be heavy 17 it must be very strong. A gas is put inside the rocket. When the gas is hot enough , it rushes out of the open end of the rocket , and pushes it 18 the air.

Rockets can fly far out into space . Rockets with men inside them have already 19 the moon . Someday rockets may be able to go 20 in space .

1．A．through B．towards C．across D．into

2．A．at B．up C．in D．by

3．A．a lot of B．lots of C．a great deal of D．a great deal

4．A．away far B．away from C．far from D．far to

5．A．then B．first C．at last D．last

6．A．when B．while C．until D．as

7．A．tie up B．take up C．put up D．hold up

8．A．carefully B．slowly C．suddenly D．quickly

9．A．that B．what C．which D．whether

10．A．go up B．going up C．will fly off D．flying off

11．A．try to get B．trying to get C．tried to get D．tries to get