must grimace
Regular verb: grimace - grimaced- grimaced

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must grimace
you must grimace
he must grimace
we must grimace
you must grimace
they must grimace 	I must be grimacing
you must be grimacing
he must be grimacing
we must be grimacing
you must be grimacing
they must be grimacing	I must have grimaced
you must have grimaced
he must have grimaced
we must have grimaced
you must have grimaced
they must have grimaced	I must have been grimacing
you must have been grimacing
he must have been grimacing
we must have been grimacing
you must have been grimacing
they must have been grimacing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I mustn't grimace
you mustn't grimace
he mustn't grimace
we mustn't grimace
you mustn't grimace
they mustn't grimace 	I mustn't be grimacing
you mustn't be grimacing
he mustn't be grimacing
we mustn't be grimacing
you mustn't be grimacing
they mustn't be grimacing	I mustn't have grimaced
you mustn't have grimaced
he mustn't have grimaced
we mustn't have grimaced
you mustn't have grimaced
they mustn't have grimaced	I mustn't have been grimacing
you mustn't have been grimacing
he mustn't have been grimacing
we mustn't have been grimacing
you mustn't have been grimacing
they mustn't have been grimacing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I grimace?
must you grimace?
must he grimace?
must we grimace?
must you grimace?
must they grimace? 	must I be grimacing?
must you be grimacing?
must he be grimacing?
must we be grimacing?
must you be grimacing?
must they be grimacing? 	must I have grimaced?
must you have grimaced?
must he have grimaced?
must we have grimaced?
must you have grimaced?
must they have grimaced? 	must I have been grimacing?
must you have been grimacing?
must he have been grimacing?
must we have been grimacing?
must you have been grimacing?
must they have been grimacing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
mustn't I grimace?
mustn't you grimace?
mustn't he grimace?
mustn't we grimace?
mustn't you grimace?
mustn't they grimace? 	mustn't I be grimacing?
mustn't you be grimacing?
mustn't he be grimacing?
mustn't we be grimacing?
mustn't you be grimacing?
mustn't they be grimacing? 	mustn't I have grimaced?
mustn't you have grimaced?
mustn't he have grimaced?
mustn't we have grimaced?
mustn't you have grimaced?
mustn't they have grimaced? 	mustn't I have been grimacing?
mustn't you have been grimacing?
mustn't he have been grimacing?
mustn't we have been grimacing?
mustn't you have been grimacing?
mustn't they have been grimacing?