Are we at the beginning of another Age of Exploration? Perhaps even more important, are we at the beginning of another Age of Colonization? As the population of the world increases towards the point where the earth can no longer support all the people 1___ on it, the second question becomes urgent. Will we discover a new world, as Columbus did, on which human life will be possible? At this point in the space age, no one can really answer these questions. We can say, 2___, that we will not see tomorrow the kind of space travel that science fiction and the movies have shown. It will be a long time before we have flight that run 3____ to human colonies on the moon or on one of the planets. We are not even going to be able to take immediate advantages of the minerals that we may find on the planets in our own solar system.

Great problems must be solved before we could send colonists out into space. The distances that must be 4____ and the length of time it takes to do that can hardly be 5___. There are also dangers that we still do not really understand—from radiation, for example, or from pieces of matter out in space, or from contamination from forms of life that might 6___ there. There is also need for humans to take their own environment into space 7____ them. So far no “island” has been discovered in space on which people can exist without systems that support life, and these systems must accompany any future space 8____. Finally, on the mast practical level, there has to be the enormous expense invested in space exploration. The US and Russian governments have already spent billions of dollars for projects from which they can receive return only in knowledge and not in money.

1.    A. inhabited     B. crowded       C. borne         D. rushed

2.    A. however      B. moreover       C. otherwise     D. therefore

3.    A. punctually    B. permanently     C. temporarily    D. regularly

4.    A. covered      B. done           C. ended          D. finished

5.    A. imagined     B. imaginable      C. imaginary       D. imaginative

6.    A. revive        B. exist          C. survive          D. live

7.    A. around       B. among         C. across           D. with

8.    A. tourists       B. pilots          C. travelers        D. invaders