英语谜语：what goes on four legs in the morning，on two at noon，and on three in the evening？什么走路开始用四条腿，后来用两条腿，最后用三条腿？

答案在第二页

答案是：people.they crawled when they were babies and walked with two legs before they had to rely on a crutch in old age.

是人，他们刚生下来的时候用四肢爬行，后来用双腿走路，老年时又不得不依靠拐杖走。