(1)______________________________________.
There are eight planets,at least thirty moons and thousands of asteroids to be explored.Their total area is about 250 times that of the earth.Spaceships will not be able to land on some of the,but that still leaves to be explored and (2)___________________________________.
Exploring space may seem terrifying to some people.No doubt explorers of the past were terrified by the great empty oceans that lay before them.They conquered their fears crossed the oceans,and built the New World.In the past when explorers set sail into the unknown they had to say good-bye to all they knew at home.Space explorers will not face such great loneliness.Ever when (3)______________________________________.
last part of this century will be the age of exploration,such as man has never know
area ten times as great continent of earth
the travel far beyond the sun,they will be able sent to message back.
发表于 2015-4-14 10:15
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发表于 2015-4-16 10:39
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