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