I still don't know who ___while I was away from home .A happened B had happened (为什么不能选择b)

问题描述:

I still don't know who ___while I was away from home .
A happened B had happened (为什么不能选择b)

I still don't know who _happend__while I was away from home .
原题有误 应该是 what happened
while 后一段时间 表示过去的时间 happened是发生在这一个时间断内的时间点上 是点时间

what happened not who happened

那个好像不是who 应该是what吧
while 动词时态并列 所以选A