must dun
Regular verb: dun - dunned- dunned

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must dun
you must dun
he must dun
we must dun
you must dun
they must dun 	I must be dunning
you must be dunning
he must be dunning
we must be dunning
you must be dunning
they must be dunning	I must have dunned
you must have dunned
he must have dunned
we must have dunned
you must have dunned
they must have dunned	I must have been dunning
you must have been dunning
he must have been dunning
we must have been dunning
you must have been dunning
they must have been dunning	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I mustn't dun
you mustn't dun
he mustn't dun
we mustn't dun
you mustn't dun
they mustn't dun 	I mustn't be dunning
you mustn't be dunning
he mustn't be dunning
we mustn't be dunning
you mustn't be dunning
they mustn't be dunning	I mustn't have dunned
you mustn't have dunned
he mustn't have dunned
we mustn't have dunned
you mustn't have dunned
they mustn't have dunned	I mustn't have been dunning
you mustn't have been dunning
he mustn't have been dunning
we mustn't have been dunning
you mustn't have been dunning
they mustn't have been dunning	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I dun?
must you dun?
must he dun?
must we dun?
must you dun?
must they dun? 	must I be dunning?
must you be dunning?
must he be dunning?
must we be dunning?
must you be dunning?
must they be dunning? 	must I have dunned?
must you have dunned?
must he have dunned?
must we have dunned?
must you have dunned?
must they have dunned? 	must I have been dunning?
must you have been dunning?
must he have been dunning?
must we have been dunning?
must you have been dunning?
must they have been dunning? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
mustn't I dun?
mustn't you dun?
mustn't he dun?
mustn't we dun?
mustn't you dun?
mustn't they dun? 	mustn't I be dunning?
mustn't you be dunning?
mustn't he be dunning?
mustn't we be dunning?
mustn't you be dunning?
mustn't they be dunning? 	mustn't I have dunned?
mustn't you have dunned?
mustn't he have dunned?
mustn't we have dunned?
mustn't you have dunned?
mustn't they have dunned? 	mustn't I have been dunning?
mustn't you have been dunning?
mustn't he have been dunning?
mustn't we have been dunning?
mustn't you have been dunning?
mustn't they have been dunning?