题目
Some people, in all seriousness, say that

humans will be living in space within the next

hundred or so years. Planet Earth will be crowded,

dirty and lack of resources. A sort of exodus --71.

of mankind will begin.

Spaceships will be assembled so that they

revolve around the earth. Some may orbit around

Mars. These space stations will be serviced by

space buses. We saw the first space bus launch in --72.

April 1981. This was "Columbia", it made several --73.

orbits around the earth and then returned, landing

on a huge dry lake bed in California. "Columbia"

will be used again. Previous spaceships have

been abandoned, only the nose cone being used

to bring the crews back to earth. --74.

Upon established, each space station will --75.

generate its own atmosphere and have its own

agriculture. It will need to rotation to provide --76.

an artificial gravity; people will be forced inwards --77.

from the center by centrifugal force.

The moon and Mars could become new sources of

new materials. Driving through space will no --78.

longer need Earth fuel- the energy would come

from the sun. This energy would be converted from --79.

electricity to work magnetic rockets.

That all sounds quite fantastically but, with --80.

the rapid development of moderns technology, who

knows about what the future holds?
答案
71. lack--short

72. launch--launched

73. it--which

74. crews--crew

75. upon--once

76. rotation--rotate

77. inwards-outwards

78. will--would

79. from--into

80. fantastically--fantastic