must perk
Regular verb: perk - perked- perked

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must perk
you must perk
she must perk
we must perk
you must perk
they must perk 	I must be perking
you must be perking
she must be perking
we must be perking
you must be perking
they must be perking	I must have perked
you must have perked
she must have perked
we must have perked
you must have perked
they must have perked	I must have been perking
you must have been perking
she must have been perking
we must have been perking
you must have been perking
they must have been perking	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I mustn't perk
you mustn't perk
she mustn't perk
we mustn't perk
you mustn't perk
they mustn't perk 	I mustn't be perking
you mustn't be perking
she mustn't be perking
we mustn't be perking
you mustn't be perking
they mustn't be perking	I mustn't have perked
you mustn't have perked
she mustn't have perked
we mustn't have perked
you mustn't have perked
they mustn't have perked	I mustn't have been perking
you mustn't have been perking
she mustn't have been perking
we mustn't have been perking
you mustn't have been perking
they mustn't have been perking	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I perk?
must you perk?
must she perk?
must we perk?
must you perk?
must they perk? 	must I be perking?
must you be perking?
must she be perking?
must we be perking?
must you be perking?
must they be perking? 	must I have perked?
must you have perked?
must she have perked?
must we have perked?
must you have perked?
must they have perked? 	must I have been perking?
must you have been perking?
must she have been perking?
must we have been perking?
must you have been perking?
must they have been perking? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
mustn't I perk?
mustn't you perk?
mustn't she perk?
mustn't we perk?
mustn't you perk?
mustn't they perk? 	mustn't I be perking?
mustn't you be perking?
mustn't she be perking?
mustn't we be perking?
mustn't you be perking?
mustn't they be perking? 	mustn't I have perked?
mustn't you have perked?
mustn't she have perked?
mustn't we have perked?
mustn't you have perked?
mustn't they have perked? 	mustn't I have been perking?
mustn't you have been perking?
mustn't she have been perking?
mustn't we have been perking?
mustn't you have been perking?
mustn't they have been perking?