在疑问句和否定句中动词的过去式和ing型时是否要变回原型？

在疑问句和否定句中动词的过去式和ing型时是否要变回原型？

过去式由于用了助动词did，就变回原形；但was, were就不用变的；
而ing是不用变的，因为它有助动词am, are, is, was, were了
如：
He liked the film.
Did he like the film?
He didn't like the film.

He was at school last year.
Was he at school last year?
He wasn't at school last year.

He is doing his homework.

Is he doing his homework?
He isn't doing his homework.

不要变回原型

do/does在否定句、疑问句中，一般作为助动词，do/does后面的动词要变成原形；而do在肯定句中，尤其是在祈使句中，是强调务必要……的意思，后面跟动词原形，而does在肯定句中一般是do(做、干等意思）的单三式。其实，do/does一是行为动词，二是助动词，无意思

举个例子吧： 1，过去式肯定句：He jumped onto a box. 改成疑问句：Did he jump onto a box? 这里，过去式变成了原型（过去式跑到前面的助动词那里了） 改成否定句：He didn't jump onto a box. 同疑问句 2，ing肯定句：He is jumping onto a box. 改成疑问句：Is he jumping onto a box? 这里，仅仅把be动词移动位置，ing不变。 改成否定句：He is not jumping onto a box. 同样，仅仅是把be动词做否定，ing不变。