do you think what happenedto her,do you think what he happened,这两句哪句是对的，为什么？

what do you think had happened to her?
do you think 做插入语

两句都错
What do you think happened to her/him?

两句都对吧?

第一个。牛津字典上这样解释1（尤指偶然）发生，出现You will never guess what happened!你根本猜不到出了什么事。
此处happen意思应为发生，此时为不及物动词，且主语应为物，英语中不说人发生什么。因而说something happens 如果要说发生在某人身上，习惯上加to，如I hope nothing has happen to them.我希望他们没出事。
另外，happen还一个意思是碰巧做，此时的结构便是sth happen to do 如She happen to be out when we called.我们打电话时他刚巧不在。
两者什么时候用就要看意思了