Scientists who study Mars have laid down the program that they can follow.
To begin with, they will have to find out whether life has ever existed on the planet of Mars in the past. Secondly they will have to (1)_____________________. And finally, they will have to make a list of the gases. Above all, (2)______________________________.
Since nitrogen is four fifths of the air we breathe, they are surprising optimistic about raising the temperature on Mars and believe it could be down in hundred years. It will take a bit longer, though, to transform the atmosphere so that human beings could live there. (3)__________________________.
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作者: susan.sui 时间: 2012-5-15 12:21
1.make a reliable map of its surface
2.they will have to discover how much nitrogen is possessive
3.scientists estimate that it would take 100,000 years作者: guangyu_ 时间: 2012-5-16 09:33
看答案作者: wyj333333 时间: 2012-5-29 21:20
make a reliable map of surface
they have to discover how much night.....
scientists estimate that will take 1000 years作者: 毛非 时间: 2012-6-2 19:22
