记忆方法
双解例句
小知识
When you measure your shadow to calculate the angle of the sun in the sky, be sure to measure to the edges of your shadow, to the penumbra, the part of a shadow that is not as dark as the center.
You're likely to come across penumbra most often in astronomy, as with an eclipse, where shadow is a defining feature. In a lunar eclipse, the edge of the earth's shadow — the part that isn't fully dark — is its penumbra. Sun spots also have a penumbra, the outer edge that's not quite as dark as the center. The word comes from the Latin root umbra, which means “shadow.” The pen part means “almost,” so a penumbra is “almost shadow.”
实用短语
单词用法
词根词缀
前缀: pen-
表示”近似,差不多”
adj.
penultimate 倒数第二的pen近似,差不多+ultimate最终→靠近最终一个→倒数第二
n.
peninsula 半岛pen近似,差不多+insula岛→似岛一样→半岛
penumbra 半明半暗之处,边缘部分pen近似,差不多+umbra影子→靠近影子→半影
词根: umbra
=shadow,表示”影子”
n.
penumbra 半明半暗之处,边缘部分pen近似+umbra影子→近似影子→半影
umbra [天]本影, 暗影umbra影子→n.[天]本影, 暗影