i know what happend中的what是什么词

i know what happend中的what是什么词 what happend? what happend Do you know what happend to him? i don't know what happend( )her we will set ()early tomorrow My dear.we never know what will happend in the future But I Do you know what happend to him?为什么用what happend to him? did you know _______?A what they happend?B what happend to t What happend 的原句是什么? what happend是什么意思 新概念2英语练习题用介词、副词填空1.I don't know what happend（ ）her.2.We will Can you explaint what happend?I--------------about something