happen这个单词主要有两种用法。
一、当happen解释为“发生”时，主要搭配是Sth happen to sb. ，如：An accident happened to him yesterday.
二、当happen解释为碰巧时和to do搭配，如：I happened to see him.
用法：意思是发生，搭配happen to，意思是碰巧做某事，例如：
1、You don't happen to know his name， do you?你不会碰巧知道他的名字吧
2、I'd hate anything to happen to him.但愿他平安无事。
