he hasn't had breakfast yet.句中的had能不能改用eat,如果可以的话有些什么区别?

he hasn't had breakfast yet.句中的had能不能改用eat,如果可以的话有些什么区别? he hasn't had breakfast yet. Tim hasn't had breakfast .Jack hasn't had ,either.同义句 改否定,例：he is still having breakfast.he hasn't had breakfast y Has he had his dinner yet?A.Yes,he hasn't B.No,he hasn't C.Y He has not had breakfast yet.是什么时态? he hasn't had breakfast怎么理解?是根本没吃饭呢还是吃了但是还没吃完? yet hasn`t he finished work.不知怎么连句? He hasn't had enough work (e ) for the job He had had breakfast before he went she has hardly had anything for breakfast ,()?a hasn't she b He left home after he had breakfast.改为同义句