题型:选择题 下面是小雨在研究“凸透镜成像规律”时的几个步骤,其中没必要的是( )A.用刻度尺测出像距B.移动光屏直到屏上出现清晰的蜡烛的图象C.温度计测出实验室的温度D.调整凸透镜、光屏、和烛焰的高度,使它们的中心大致在同一高度 查看答案
题型:选择题 Film has a much shorter history, especially when _____ such art forms as music and painting.A.having compared withB.comparing withC.compare withD.compared with 查看答案