题目

Farmer John and Farmer Bob were neighbours．For more than 30 years, they had been getting along very well． Then their good relationship broke．It began with a small thing, then bitter words, and then weeks of silence．One morning Farmer John woke up to find a stream between the two farms．“It must be Bob,” John thought． Then one day there was a knock on John’s door．He opened it to find a carpenter（木匠） standing at the doorway． “I’m looking for a few days’ work,” the carpenter said． “I do have a job for you,” John said．“Look across the stream at 如图所示是同一发光点S发出的光经过平面镜反射后的两条反射光线，请用作图法画出发光点S的位置．