搜题请搜索小程序“爱下问搜题”
问题 问答题

在图中大致画出法线及入射光线，并标出入射角的度数．

答案

根据光的反射定律，首先通过反射光线OB与镜面的交点（入射点）O做垂直于镜面的法线OO′，做入射光线使反射角等于入射角，则AO即为入射光线；

由题知，反射光线与镜面的夹角为40°，则反射角为50°，因为反射角等于入射角，所以入射角为50°，

如下图所示：

填空题

The teenage year from 13 to 19 were the most difficult time for me . They were also the best and worse years in my life . At the first, I thought I knew everything and could make decisions by yourself. However, my parents didn’t seem to think such. They always tell me what to do and how to do it. At one time , I even felt my parents couldn’t understand me so I hoped I could be freely from them. I showed them I was independent by wear strange clothes. Now I am leaving home to college. At last, I will be on my own, but I still want to have my parents to turn to whenever need help.

5（）
查看答案
选择题

“一滴水只有放进大海才永远不会干涸。”没有班集体中人与人之间的团结协作，个人的智慧就难以发挥作用。下列选项中表明这个道理的有 （    ）

①蝼蚁之穴溃千里之堤             ②花要叶捧，人靠人帮

③一个篱笆三个桩，一个好汉三个帮 ④有志者事竟成

A．①②③

B．②③④

C．②③

D．①②③④
查看答案