皇帝命令女仆们把精美的丝绸和缎子剪成花和叶子，用来装饰树木和湖泊，将春天和夏天的样子恰到好处地复刻出来。
The emperor ordered the girl servants to cut fine silk and satin into flowers and leaves and use them to decorate the trees and lakes, copying nicely the looks of spring and summer.
科学家去年夏天发现，类似寄生菌最早存在于4800万年德国梅塞尔地区的植物叶子上。
Last summer the oldest evidence of such parasites was found on the leaves of plants that grew in Messel, Germany, 48million years ago.
当夏天转变成秋天时，由于白天时间变短而且天气日益变凉，这些叶子的光合作用过程减慢了。相反，这个过程导致了较少的叶绿素，绿色褪成黄色。
As summer turns to autumn, the photosynthetic process slows down as the days get both shorter and colder, which in turn leads to less chlorophyll production and the green fading to yellow.
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