如图所示根据光的反射定律画出发射光线.
根据光的反射定律,首先通过入射点O做垂直于镜面的法线,做反射光线使反射角等于入射角.
故答案为:
下列物品中,由硬度最大的物质组成的是 [ ]
A.橡皮泥
B.铅笔芯
C.塑料尺
D.钢锯条
— Were you late the meeting?
— No, I arrived there ten minutes ______ the meeting started. [ ]
A. for, before
B. at, before
C. for, till
D. at, after