Lumen: The unit for measuring luminous flux. One lumen is the flux emitted in one solid angle by a point light source of one candela.是什么意思_Lumen: The unit for measuring luminous flux. One lumen is the flux emitted in one solid angle by a point light source of one candela.在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句