only then和only when的用法

Question

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？
谢谢了

Answer 1

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

Answer 2

Only when +时间+部分倒装（did sb done）
only then 直到那时用had sb v-ed

Answer 3

if
only
表“但愿”，用于虚拟语气；
only
if表“只有”，用于真实或非真实条件句。如。if
only
i
were
rich.
/only
if
the
light
turns
green,
then
you
can
cross
the
road.