Did you know what ___?

问题描述:

Did you know what ___?
---Sorry,Ididn't
A happen B happened C happening D did happen
并说明一下理由哦

选B
what ___作为know的宾语,应为陈述语气,排除D
宾语what ___是一个从句,what为主语,谓语应选动词,排除C
did时态是过去式