问题描述：
1No one has yet succeeded in explaining the
___ of how life began.
A cause B problem C Puzzle D reason
2I've never heard such stories ___ Dad tells me.
A as B that C which D what
___ of how life began.
A cause B problem C Puzzle D reason
2I've never heard such stories ___ Dad tells me.
A as B that C which D what
问题解答：
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