强调句:it was when sundany that...还是it was sunday that...

题目

强调句:it was when sundany that...还是it was sunday that...
貌似有的时候要WHEN,有的时候不要啊?怎么看

答案

it was on sunday that we went to the park.
强调句
it was sunday when we went to the park.
定语从句
关键就在于前面的介词on
有on的话去掉it is ...that句子是完整的所以就是强调句,没有的话就是定语从句