must jam
Regular verb: jam - jammed- jammed

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must jam
you must jam
he must jam
we must jam
you must jam
they must jam 	I must be jamming
you must be jamming
he must be jamming
we must be jamming
you must be jamming
they must be jamming	I must have jammed
you must have jammed
he must have jammed
we must have jammed
you must have jammed
they must have jammed	I must have been jamming
you must have been jamming
he must have been jamming
we must have been jamming
you must have been jamming
they must have been jamming	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I mustn't jam
you mustn't jam
he mustn't jam
we mustn't jam
you mustn't jam
they mustn't jam 	I mustn't be jamming
you mustn't be jamming
he mustn't be jamming
we mustn't be jamming
you mustn't be jamming
they mustn't be jamming	I mustn't have jammed
you mustn't have jammed
he mustn't have jammed
we mustn't have jammed
you mustn't have jammed
they mustn't have jammed	I mustn't have been jamming
you mustn't have been jamming
he mustn't have been jamming
we mustn't have been jamming
you mustn't have been jamming
they mustn't have been jamming	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I jam?
must you jam?
must he jam?
must we jam?
must you jam?
must they jam? 	must I be jamming?
must you be jamming?
must he be jamming?
must we be jamming?
must you be jamming?
must they be jamming? 	must I have jammed?
must you have jammed?
must he have jammed?
must we have jammed?
must you have jammed?
must they have jammed? 	must I have been jamming?
must you have been jamming?
must he have been jamming?
must we have been jamming?
must you have been jamming?
must they have been jamming? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
mustn't I jam?
mustn't you jam?
mustn't he jam?
mustn't we jam?
mustn't you jam?
mustn't they jam? 	mustn't I be jamming?
mustn't you be jamming?
mustn't he be jamming?
mustn't we be jamming?
mustn't you be jamming?
mustn't they be jamming? 	mustn't I have jammed?
mustn't you have jammed?
mustn't he have jammed?
mustn't we have jammed?
mustn't you have jammed?
mustn't they have jammed? 	mustn't I have been jamming?
mustn't you have been jamming?
mustn't he have been jamming?
mustn't we have been jamming?
mustn't you have been jamming?
mustn't they have been jamming?