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来源：雅诚德英语网
And this poses a puzzle: how can characteristics that disappeared millions of years ago suddenly reappear?
这就造成了一个难题：数百万年前消失的特征是如何突然重现的？
And this poses a puzzle: how can characteristics that disappeared millions of years ago suddenly reappear?
这就造成了一个难题：数百万年前消失的特征是如何突然重现的？