I must stay you must stay he must stay we must stay you must stay they must stay
V-ing form
I must be staying you must be staying he must be staying we must be staying you must be staying they must be staying
Perfect
I must have stayed you must have stayed he must have stayed we must have stayed you must have stayed they must have stayed
V-ing perfect
I must have been staying you must have been staying he must have been staying we must have been staying you must have been staying they must have been staying
Negation
Simple form
I mustn't stay you mustn't stay he mustn't stay we mustn't stay you mustn't stay they mustn't stay
V-ing form
I mustn't be staying you mustn't be staying he mustn't be staying we mustn't be staying you mustn't be staying they mustn't be staying
Perfect
I mustn't have stayed you mustn't have stayed he mustn't have stayed we mustn't have stayed you mustn't have stayed they mustn't have stayed
V-ing perfect
I mustn't have been staying you mustn't have been staying he mustn't have been staying we mustn't have been staying you mustn't have been staying they mustn't have been staying
Interrogative form
Simple form
must I stay? must you stay? must he stay? must we stay? must you stay? must they stay?
V-ing form
must I be staying? must you be staying? must he be staying? must we be staying? must you be staying? must they be staying?
Perfect
must I have stayed? must you have stayed? must he have stayed? must we have stayed? must you have stayed? must they have stayed?
V-ing perfect
must I have been staying? must you have been staying? must he have been staying? must we have been staying? must you have been staying? must they have been staying?
Interro-negative form
Simple form
mustn't I stay? mustn't you stay? mustn't he stay? mustn't we stay? mustn't you stay? mustn't they stay?
V-ing form
mustn't I be staying? mustn't you be staying? mustn't he be staying? mustn't we be staying? mustn't you be staying? mustn't they be staying?
Perfect
mustn't I have stayed? mustn't you have stayed? mustn't he have stayed? mustn't we have stayed? mustn't you have stayed? mustn't they have stayed?
V-ing perfect
mustn't I have been staying? mustn't you have been staying? mustn't he have been staying? mustn't we have been staying? mustn't you have been staying? mustn't they have been staying?