only later did they realize what a terrible thing it was

问题描述:

only later did they realize what a terrible thing it was
这里的what做什么成分?
如果着句句子不倒装?那助动词DID应该放在哪?

这是一个only + 时间状语 放在句首,句子主干采用倒装结构的句子.
意思是 只有到那时他们才意识到这是一件多么可怕的事情.
what做感叹句的引导词.其实 动词 realize 后的宾语成分是由感叹句充当的.
如果不倒装,did realize 就要合并成动词的过去式 realized.
正句的正常语序是
They realized what a terrible thing it was later.( 倒装句中的
only 是倒装形式的引导词同时也起着强调的作用.)