What did Helen do on the farm last holiday?
When did your father read a storybook about animals?请问，What did Helen do on the farm last holiday?句子中的“do”不要用过去式么、？前面的did已经用了过去式，所以后面的do用原型，疑问句都只需要更改疑问词后面的动词形式来表示时态