题目

如图所示，请画出两条光线经过凹透镜后的折射光线。（______） 答案：【答案】【解析】根据：入射光线平行凹透镜的主光轴，则折射光线反向延长通过焦点；过光心的入射光线经凹透镜折射后方向不变；如图：  Shelly had prepared carefully for her exam so that she could be sure of passing it on her first_______. A. intention         B. attempt    C. purpose       D. desire