I don’t know what ___ last night.用he happened 还是happened to him 为什么

I don’t know what ___ last night.用he happened 还是happened to him 为什么
I don’t know what ___ last night.
用he happened 还是happened to him
为什么

I don’t know what ___ last night.用he happened 还是happened to him 为什么
happened to him
happened 是说 what所指代的东西happen,而不是he happen ,“他”有什么好发生的呢?
所以应该是what所指代的东西happen在“他”的身上

happened to him
固定用法

happened to him.