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1.What it was to become ...
2.What is even more important...
3.It was not..obvious that water was to be fundamental to the development of life.(it为形å¼ä¸»è¯, thatä»å¥å°±æ¯ä¸»è¯ä»å¥ä½çæ£ç主è¯)
4.Wha many scientists believe...
5.Why they suddenly disappeared...
6.(So) whether life will continue on the earth for millions of years to come...
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