看绝望的主妇学英语地道表达：What a Small World

What a Small World: Used when a person knows someone you know by chance; The world is very large with a lot of people in it. When two people know the same person by chance, then the world doesn’t seem so big. In this case, the phrase “what a small world” is commonly used.

中文释义：What a Small World：世界真是太小了！通常用在口语中，不是真的要谈论世界的大小，而是引申为不期而遇，真是太巧了。用它来形容一个意外的巧合，尤其是当两个相识的人不期而遇的时候；或两个人之间有共同的朋友，相互之间因一件事或一个人而被联系起来。
例句：I didn’t know that you knew my uncle. What a small world.