籾朕坪否
The most valuable rubbish in the world is not in the world, but in orbit around it�� Space has always contained "trash": a little dust raised from Earth by air currents, cosmic ray fragments, and some cosmic dust caused by meteors�� Explosions from the sun's surface may have added some atomic nuclei, carried outward into space by the solar wind�� But there is much more trash now�� When the hatch of a space capsule opens, dust particles float out�� Sometimes small objects escape�� Astronaut Edward White's heat-reflecting glove, dropped during the first space walk, is up there�� There are several thousand fragments from upper rocket stages, some satellites that did not work, and some satellites still working�� A Titan rocket that destroyed itself added 339 pieces to the orbiting rubbish��
Several hundred man-made objects that were space travelers have disappeared: they burned up as they reentered Earth's atmosphere�� One famous piece that returned successfully was found in the United States, when two policemen kicked it out of the middle of a street in Wisconsin�� It was a twenty-pound piece of Russia's Sputnik IV��
1��Present-day space trash is called valuable because of_______��
A��materials used in it B�� the total cost of producing it
C��its possible use as atomic energy D��None of the above
2��Before our time, Earth's only addition to space rubbish was_______��
A��some atomic nuclei B�� cosmic ray fragments
C��cosmic dustD�� None of the above
3�� The writer says a space capsule adds to rubbish when________��
A��a hatch opens B��rockets fire
C��food is jettisoned D��any astronaut goes for a walk
4��The article dropped during the first space walk was a_________��
A�� camera B�� piece of nylon cord
C��heat-reflecting glove D�� glare-proof plastic visor
5��When a Titan rocket destroyed itself, the trash was increased by_____��
A��339 pieces B��399 pieces
C��several thousand pieces D��twenty pounds
6��Implied but not stated:
A��Some working satellites are still in orbit��
B��There is some way of counting objects in orbit��
C��All objects that have disappeared from orbit have burned up on reentering our atmosphere��
D��Radar is used to track objects in space��
7��The policemen probably kicked the object they found because it_______��
A��was useless B�� had come from space
C��might cause an accident D�� looked dangerous
8��This famous object was from_______��
A��a Titan rocket B�� an American lunar capsule
C��Russia's Sputnik II D�� Russia's Sputnik IV
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