Once there was a man came from Zheng State. One day, he wanted to buy a pair of shoes. So he
took out a ruler and measured the size of his shoes. Then he went to the market. When he came into a
shoe shop and wanted to buy shoes, he suddenly shouted, "Oh, I forgot to take my ruler. I have to go
back to get my ruler. " Then he ran away. The shopkeeper shouted, "Wait, please! You can try them on
yourself. " "No!" The man kept on running. When he got the ruler and went back to the shoe shop again,
the shop was already closed.
(答案不唯一)