亡羊补牢，为什么不算晚？

A farmer kept sheep in a pen. 有个农夫，养了一圈羊。 One morning, one sheep was gone. 一天早上，少了一只羊。 A wolf had made a hole in the pen. 原来狼在羊圈上，掏了个洞。 His neighbor said, "Fix the pen!" 邻居劝他：“快把羊圈补好吧！” The farmer said, "Sheep are already gone." 农夫却说：“羊都丢了，补啥呀。” That night, another sheep ran away. 结果那天晚上，又跑了一只羊。 Fix it in time, and you lose less.