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