I must study you must study he must study we must study you must study they must study
V-ing form
I must be studying you must be studying he must be studying we must be studying you must be studying they must be studying
Perfect
I must have studied you must have studied he 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 he 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 he 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 he 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 he 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 he 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 he study? must we study? must you study? must they study?
V-ing form
must I be studying? must you be studying? must he be studying? must we be studying? must you be studying? must they be studying?
Perfect
must I have studied? must you have studied? must he 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 he 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 he 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 he 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 he 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 he have been studying? mustn't we have been studying? mustn't you have been studying? mustn't they have been studying?