下列关于光线的说法正确的是( ) A . 光源能射出无数条光线 B . 光线就是很细的光束 C . 光线是看不见的,人们用一条看得见的实线来表示光线,用到理想模型法 D . 光线是用来表示光传播方向的直线,常用虚线表示 答案:C4. (2015 镇江,13) —The radio says there will be a rainstorm this weekend,so we have to cancel the hiking to Nanshan. --I'm looking forward to it. A. Never mind. B. What a pity! C. My pleasure. D. No problem.