4-4=?
One day, the teacher inquired Peter: How much is four minus four? Peter was tongue-tied.
the teacher got angry and said: What a fool! You see, if I put four coins in your pocket, but there is a hole in your pocket and all of them leak out, now what is left in your pocket?
The hole, replied Peter.四减四等于几？
一天，都是问彼德：四减四等于几？彼德张口结舌答不上来。
老师生气地说：真笨！你想，如果我放四个硬币在你的口袋里，但你的口袋里有个窟窿，结果四个硬币都漏掉了。那么，你的口袋里还有什么？
窟窿，彼德答道。