题目

如图所示，CD为竖直挂在墙上的平面镜，位于A处的甲同学通过平面镜看到了位于B处的乙同学．在这一现象中，光线的入射角是（ ) A . ∠1 B . ∠2 C . ∠3 D . ∠4 答案：B Mr Black must be worried about something．You can ________ it from the look on his face． [　　] A． reason B． recognize C． read D． realize