是when did it started还是when did it start?

问题描述:

是when did it started还是when did it start?

用了did 后面加动词原形

后者when did it start是正确的,因为前有助动词did,动词用原形。

when did it start

A

是when did it start?
因为前面的助动词已经由do变为了did,所以后面的动词使用原形就好了