only then和only when的用法

问题描述:

only then和only when的用法
only then和only when,如何搭配had sb v-ed或者did sb v-ed
举个例子only then_he realize the importance of learning English
此处用did还是had?如果改成when呢?

用did,
如果改成only when ,
Only when he realized the importance of learning English
did he decide to study hard.
而且二者意义不同
only when 意思是直到...时候才.
only then 意思是知道那是
希望能给楼主些许帮助