【英语时差8,16】秋季落叶的奥秘-上

 Every autumn, citizens of the North American Midwest and Northeast enjoy a spectacularly colorful display as leaves turn various shades of red, orange, yellow, purple, and brown. But autumn also entails¹ the backbreaking work of raking all those beautiful leaves once they fall. Why can’t leaves change colors, stay on their trees, and change back to green again when spring comes? Unfortunately, the chemical processes responsible for changing leaf color also make leaves fall. Trees prepare for their dormant² winter period by undergoing senescence. Senescence involves recycling nutrients³ from leaves into the plant body for use in the Spring. As trees enter dormancy⁴, they cut back on chlorophyll production.

1 entails   

使…成为必要( entail的第三人称单数 )； 需要； 限定继承； 使必需

参考例句：

• The job entails a lot of hard work. 这工作需要十分艰苦的努力。
• This job entails a lot of hard work. 这项工作需要十分努力。

2 dormant   

adj.暂停活动的；休眠的；潜伏的

参考例句：

• Many animals are in a dormant state during winter.在冬天许多动物都处于睡眠状态。
• This dormant volcano suddenly fired up.这座休眠火山突然爆发了。

3 nutrients   

n.（食品或化学品）营养物，营养品( nutrient的名词复数 )

参考例句：

• a lack of essential nutrients 基本营养的缺乏
• Nutrients are absorbed into the bloodstream. 营养素被吸收进血液。 来自《简明英汉词典》

4 dormancy   

n.睡眠，冬眠，隐匿

参考例句：

• During dormancy the plants must be kept very dry. 在休眠期，植物必须保持非常干燥。 来自辞典例句
• It may also come to the point of virtual dormancy. 它也可以达到实际上的潜伏状态。 来自辞典例句