【英语时差8,16】秋季落叶的奥秘-上
时间：2019-02-23 作者：英语课 分类：英语时差8，16
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 entails 1 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 dormant 2 winter period by undergoing senescence. Senescence involves recycling nutrients 3 from leaves into the plant body for use in the Spring. As trees enter dormancy 4, they cut back on chlorophyll production.
- 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。
- 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。
- 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》