4周搞定2000+托福核心词
over = over(在…上) = 来到上面→战胜
over = over(在…上) = 忽略
circumstance = circum(环绕) + st(站，立) + ance(表名词) = 环绕着站→（周边）情况→环境
substance = sub(下面) + st(站，立) + ance(表名词) = 站在下面的东西→物质，本质
accessory = ac(来) + cess(行走) + ory(表名词) = 跟着行走的东西→附加物,附属的
directory = di(分开) + rect(直) + ory(表名词) = 分类显示的东西→通讯录
上层林冠
overstory
常考释义
n. 上层林冠；上层
Reproduce naturally in the open rather than under an overstory.
宁在空旷地而不是树冠下自然繁殖。
The third stage of forest development is characterized by openings in the overstory canopy, caused by tree mortality, and the renewed growth of understory in response to increased light reaching the forest floor.
森林发展的第三阶段的特征是，树木死亡使上层林冠有了缺口，能让更多阳光到达森林的地面，林下的植物重新开始生长。
来源于：阅读EXTRA3 P3以上图片仅供学习交流使用，版权归原作者所有，如有侵权，请与我方联系
