题目

把高2 cm的发光棒立于焦距为5 cm的凸透镜前，在凸透镜后的光屏上成了4 cm高的像，物体离凸透镜的距离可能是          A．7.5 cm                       B．12.5 cm                  C．4.5 cm                   D． 10 cm 答案：AWhen a pencil is partly in a glass of water, it looks as if it _______. [　　] A．breaksB．has broken C．were brokenD．had been broken