_ frightened me was a loud crash from the next room.为什么用what而不用which.

问题描述:

_ frightened me was a loud crash from the next room.为什么用what而不用which.

what 修饰后面的内容啊,
什么让我害怕的响声从隔壁的房间里.是后面我所害怕的声音的定语
.