六级练习2012.05.12 fiction, naturally, recommend

Rebecca949

Science fiction writers have often imagined humans going to live on the Mars. But these days, (1)____________________________.
It has a great deal to recommend it, since it might solve the problem of overcrowding on the earth. But obviously, it would not be worth making the effort unless people could live there naturally. (2)_________________________, this might be possible.
But in fact it is mostly carbon dioxide. Apart from that, there are other problems to be overcome. For example, (3)___________________________to 15 degrees above it.

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guangyu_

不错，

riverfeng

1、Sciensist are taking the idea into sincerely
2、If ...like on the earth
3、temperature would have to raise ...low

wyj333333

scientists are taking the ieda seriously
if..........like that in the earth
the tempreture would been risen from 60 degrees below zero

susan.sui

1.scientists are taking the idea seriously.
2.if the atmosphere were like the earth
3.the temperature would have to be raised from 60 degrees below zero.