十万个为什么·科学阅读30篇（6）
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Why Do Leaves Change Color in Fall?
秋天树叶为什么会变色？
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Leaves make food using green chlorophyll all spring and summer.春夏两季，树叶依靠绿色叶绿素制造养分。
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In fall, days get shorter and cooler.秋季白天变短、气温转凉。
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Trees stop making chlorophyll and break it down.树木停止合成叶绿素并将其分解。
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Yellow and orange pigments were there all along.黄色和橙色色素原本就一直存在。
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They show up once green fades away.待绿色褪去后，它们便显现出来。
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Red color comes from new sugar trapped in leaves.红色来自叶片中滞留的新糖分。
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Weather affects how bright the colors become.天气影响秋叶色彩的鲜艳程度。
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After color change, trees seal leaf stems and drop them.变色后，树木封闭叶柄并脱落叶片。