【案例一】一堂政治课正上得有声有色。老师讲得起劲,学生听得认真。突然,教室里出现了一束亮光,在墙壁、蓬顶间跳跃着,最后光束竟在黑板上跳来跳去。正当同学们试图寻找“光源”时“,啪”,一声玻璃的破碎声在教室的后边响起。同学们不约而同地向着声音响起的地方循去。原来后? [Case 1] A political lesson was very impressive. The teacher talked hard and the students listened carefully. Suddenly, a beam of light appeared in the classroom, jumping between the walls and the ceiling, and finally the light beam jumped up and down the board. Just as the students tried to find the “light source,” “Oh,” a shattering sound of glass shone behind the classroom. Students invariably walked to the place where the sounds were heard. After the original?