I didn`t know __________ because it was dark.A)what`s happenedB)what was happenedC)what had happenedD)happened what选什么?为什么?

I didn`t know __________ because it was dark.A)what`s happenedB)what was happenedC)what had happenedD)happened what选什么?为什么?
I didn`t know __________ because it was dark.
A)what`s happened
B)what was happened
C)what had happened
D)happened what
选什么?为什么?

I didn`t know __________ because it was dark.A)what`s happenedB)what was happenedC)what had happenedD)happened what选什么?为什么?
c
1.happen没有被动语态 B错误
2.前面有did,所以happen用过去的过去.选c

c

C

C 用过去完成时