happen n on偶然发现;巧遇
what happen going on babe怎样去悲;会发生什么
happen on somebody发生在某人身上
Revelations always happen on mountains山上总是出现新发现
happen on a cold morning发生在一个寒冷的早上
V（动词） to find by chance 偶然找到
I happened upon a five-pound note lying in the street