must dam
Regular verb: dam - dammed- dammed

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must dam
you must dam
she must dam
we must dam
you must dam
they must dam 	I must be damming
you must be damming
she must be damming
we must be damming
you must be damming
they must be damming	I must have dammed
you must have dammed
she must have dammed
we must have dammed
you must have dammed
they must have dammed	I must have been damming
you must have been damming
she must have been damming
we must have been damming
you must have been damming
they must have been damming	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I mustn't dam
you mustn't dam
she mustn't dam
we mustn't dam
you mustn't dam
they mustn't dam 	I mustn't be damming
you mustn't be damming
she mustn't be damming
we mustn't be damming
you mustn't be damming
they mustn't be damming	I mustn't have dammed
you mustn't have dammed
she mustn't have dammed
we mustn't have dammed
you mustn't have dammed
they mustn't have dammed	I mustn't have been damming
you mustn't have been damming
she mustn't have been damming
we mustn't have been damming
you mustn't have been damming
they mustn't have been damming	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I dam?
must you dam?
must she dam?
must we dam?
must you dam?
must they dam? 	must I be damming?
must you be damming?
must she be damming?
must we be damming?
must you be damming?
must they be damming? 	must I have dammed?
must you have dammed?
must she have dammed?
must we have dammed?
must you have dammed?
must they have dammed? 	must I have been damming?
must you have been damming?
must she have been damming?
must we have been damming?
must you have been damming?
must they have been damming? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
mustn't I dam?
mustn't you dam?
mustn't she dam?
mustn't we dam?
mustn't you dam?
mustn't they dam? 	mustn't I be damming?
mustn't you be damming?
mustn't she be damming?
mustn't we be damming?
mustn't you be damming?
mustn't they be damming? 	mustn't I have dammed?
mustn't you have dammed?
mustn't she have dammed?
mustn't we have dammed?
mustn't you have dammed?
mustn't they have dammed? 	mustn't I have been damming?
mustn't you have been damming?
mustn't she have been damming?
mustn't we have been damming?
mustn't you have been damming?
mustn't they have been damming?