英语脑筋急转弯,

题目

英语脑筋急转弯,
you are standing at a well with two pots.One holds seven litres and the other holds five litres.Neither pot has any markings so the only amount of water you can measure accurately is when a pot is full.How can you measure out exactly four litres?

答案

翻译：你站在井的两盆.其他拥有五公升和一个七公升.既不锅有任何标记,因此,只有水你可以准确测量量满一壶时.你怎么可以衡量出确切地四公升?回答;你可以先将7升的壶灌满,倒5升至5升的壶,将5升壶倒空,再将剩余的2升倒...