I must study you must study she must study we must study you must study they must study
V-ing form
I must be studying you must be studying she must be studying we must be studying you must be studying they must be studying
Perfect
I must have studied you must have studied she must have studied we must have studied you must have studied they must have studied
V-ing perfect
I must have been studying you must have been studying she must have been studying we must have been studying you must have been studying they must have been studying
Negation
Simple form
I mustn't study you mustn't study she mustn't study we mustn't study you mustn't study they mustn't study
V-ing form
I mustn't be studying you mustn't be studying she mustn't be studying we mustn't be studying you mustn't be studying they mustn't be studying
Perfect
I mustn't have studied you mustn't have studied she mustn't have studied we mustn't have studied you mustn't have studied they mustn't have studied
V-ing perfect
I mustn't have been studying you mustn't have been studying she mustn't have been studying we mustn't have been studying you mustn't have been studying they mustn't have been studying
Interrogative form
Simple form
must I study? must you study? must she study? must we study? must you study? must they study?
V-ing form
must I be studying? must you be studying? must she be studying? must we be studying? must you be studying? must they be studying?
Perfect
must I have studied? must you have studied? must she have studied? must we have studied? must you have studied? must they have studied?
V-ing perfect
must I have been studying? must you have been studying? must she have been studying? must we have been studying? must you have been studying? must they have been studying?
Interro-negative form
Simple form
mustn't I study? mustn't you study? mustn't she study? mustn't we study? mustn't you study? mustn't they study?
V-ing form
mustn't I be studying? mustn't you be studying? mustn't she be studying? mustn't we be studying? mustn't you be studying? mustn't they be studying?
Perfect
mustn't I have studied? mustn't you have studied? mustn't she have studied? mustn't we have studied? mustn't you have studied? mustn't they have studied?
V-ing perfect
mustn't I have been studying? mustn't you have been studying? mustn't she have been studying? mustn't we have been studying? mustn't you have been studying? mustn't they have been studying?