must ref
Verbo regular: ref - refed- refed

Afirmação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I must ref
you must ref
he must ref
we must ref
you must ref
they must ref 	I must be refing
you must be refing
he must be refing
we must be refing
you must be refing
they must be refing	I must have refed
you must have refed
he must have refed
we must have refed
you must have refed
they must have refed	I must have been refing
you must have been refing
he must have been refing
we must have been refing
you must have been refing
they must have been refing	

Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I mustn't ref
you mustn't ref
he mustn't ref
we mustn't ref
you mustn't ref
they mustn't ref 	I mustn't be refing
you mustn't be refing
he mustn't be refing
we mustn't be refing
you mustn't be refing
they mustn't be refing	I mustn't have refed
you mustn't have refed
he mustn't have refed
we mustn't have refed
you mustn't have refed
they mustn't have refed	I mustn't have been refing
you mustn't have been refing
he mustn't have been refing
we mustn't have been refing
you mustn't have been refing
they mustn't have been refing	

Forma interrogativa 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
must I ref?
must you ref?
must he ref?
must we ref?
must you ref?
must they ref? 	must I be refing?
must you be refing?
must he be refing?
must we be refing?
must you be refing?
must they be refing? 	must I have refed?
must you have refed?
must he have refed?
must we have refed?
must you have refed?
must they have refed? 	must I have been refing?
must you have been refing?
must he have been refing?
must we have been refing?
must you have been refing?
must they have been refing? 	

Forma interro-Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
mustn't I ref?
mustn't you ref?
mustn't he ref?
mustn't we ref?
mustn't you ref?
mustn't they ref? 	mustn't I be refing?
mustn't you be refing?
mustn't he be refing?
mustn't we be refing?
mustn't you be refing?
mustn't they be refing? 	mustn't I have refed?
mustn't you have refed?
mustn't he have refed?
mustn't we have refed?
mustn't you have refed?
mustn't they have refed? 	mustn't I have been refing?
mustn't you have been refing?
mustn't he have been refing?
mustn't we have been refing?
mustn't you have been refing?
mustn't they have been refing?