在树叶凋落之前，树会分解叶绿素分子，把有用的氮运回树枝中。
Before letting its leaves go, the tree dismantles their chlorophyll molecules and ships their valuable nitrogen back into the twigs.
夏天的树叶是绿色的，因为它们富含叶绿素，这种捕捉阳光的分子可以将这些能量转化为新的树木生长材料。
Summer leaves are green because they are full of chlorophyll, the molecule that captures sunlight converts that energy into new building materials for the tree.
活跃的叶绿素分子产生的氧气破坏性强，秋天衰弱的树叶随后变得更容易受到影响。
The weakened fall leaf then becomes vulnerable to the highly destructive effects of the oxygen created by the excited chlorophyll molecules.
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