刻舟求剑：船走了，剑不会等

A man once crossed a river in a boat. 从前有个人，坐船过河。 Suddenly his sword fell into the water. 忽然，他的剑掉进了水里。 He quickly cut a mark on the boat. 他赶紧在船边，刻了个记号。 "My sword fell right here", he said. 他说：“我的剑就是从这儿掉下去的。” The boat kept going, but the sword stayed. 船一直在走，剑却留在原地。 Later he jumped in at the mark. 后来他照着记号，跳下水找剑。 The boat moved, so the mark was useless. 船都走远了，记号当然没用啦。