一般疑问句中 Did的后面的动词的形式用什么?

题目

一般疑问句中 Did的后面的动词的形式用什么?
例如 你在家里吃午饭了吗吗?
Did you have breakfast at home?
还是Did you had breakfast at home?

答案

Did 后面的动词形式一般要用原形
如应该为：Did you have breakfast at home?