对于科学家来说，他们只是好奇于其中的遗传机制，一个细胞一个细胞地死去直到整片树叶凋零。

For their part, scientists have puzzled over the genetic mechanism that kills off cells one by one until a leaf drops.

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这是一个秋天，树叶正凋零。

It was autumn and the leaves were dying.

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不久，树叶纷纷飘零，海湾刮来阵阵寒风。鲁本在街头四处逛荡，努力寻找着被他视为宝物的麻袋。

Soon the leaves fell and the winds blew cold and gusty from the bay Reuben wanDered the streets, diligently searching for his hessian treasures.

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