must guffaw
Regular verb: guffaw - guffawed- guffawed

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must guffaw
you must guffaw
she must guffaw
we must guffaw
you must guffaw
they must guffaw 	I must be guffawing
you must be guffawing
she must be guffawing
we must be guffawing
you must be guffawing
they must be guffawing	I must have guffawed
you must have guffawed
she must have guffawed
we must have guffawed
you must have guffawed
they must have guffawed	I must have been guffawing
you must have been guffawing
she must have been guffawing
we must have been guffawing
you must have been guffawing
they must have been guffawing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I mustn't guffaw
you mustn't guffaw
she mustn't guffaw
we mustn't guffaw
you mustn't guffaw
they mustn't guffaw 	I mustn't be guffawing
you mustn't be guffawing
she mustn't be guffawing
we mustn't be guffawing
you mustn't be guffawing
they mustn't be guffawing	I mustn't have guffawed
you mustn't have guffawed
she mustn't have guffawed
we mustn't have guffawed
you mustn't have guffawed
they mustn't have guffawed	I mustn't have been guffawing
you mustn't have been guffawing
she mustn't have been guffawing
we mustn't have been guffawing
you mustn't have been guffawing
they mustn't have been guffawing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I guffaw?
must you guffaw?
must she guffaw?
must we guffaw?
must you guffaw?
must they guffaw? 	must I be guffawing?
must you be guffawing?
must she be guffawing?
must we be guffawing?
must you be guffawing?
must they be guffawing? 	must I have guffawed?
must you have guffawed?
must she have guffawed?
must we have guffawed?
must you have guffawed?
must they have guffawed? 	must I have been guffawing?
must you have been guffawing?
must she have been guffawing?
must we have been guffawing?
must you have been guffawing?
must they have been guffawing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
mustn't I guffaw?
mustn't you guffaw?
mustn't she guffaw?
mustn't we guffaw?
mustn't you guffaw?
mustn't they guffaw? 	mustn't I be guffawing?
mustn't you be guffawing?
mustn't she be guffawing?
mustn't we be guffawing?
mustn't you be guffawing?
mustn't they be guffawing? 	mustn't I have guffawed?
mustn't you have guffawed?
mustn't she have guffawed?
mustn't we have guffawed?
mustn't you have guffawed?
mustn't they have guffawed? 	mustn't I have been guffawing?
mustn't you have been guffawing?
mustn't she have been guffawing?
mustn't we have been guffawing?
mustn't you have been guffawing?
mustn't they have been guffawing?