_____the exercise-books_____(must return)to the students tomorrow?请分析完整正确。be returned，为什么用这个？

_____the exercise-books_____(must return)to the students tomorrow?请分析完整正确。be returned，为什么用这个？
_____the exercise-books_____(must return)to the students tomorrow?
请分析
完整正确。be returned，为什么用这个？

_____the exercise-books_____(must return)to the students tomorrow?请分析完整正确。be returned，为什么用这个？
must the exercise books be returned to the students tomorrow?
这些练习册明天必须要发给学生们么?
be returned,表示有返还的意思,也许这个句子有前因表示这些练习册是学生交上来的作业,现在由老师批阅过发还给学生的意思,如果用send out 或者deliver的话,表示是新的练习册,刚刚发给学生.在这里用 be returned ,练习册是主语要用被动式,而must是情态动词后面跟动词原形,所以用be returned最合适.

Must the exercise-books be returned to the students tomorrow? Yes,they must/No,they need not 首先练习本被返还，是被动，其次情态动词must后须用原型

Must the exercise-books be returned to the students tomorrow
情态动词疑问句……

Must the exercise-books return to the students tomorrow?
这个就是把must提前造成疑问句。