can ref
Verbo regular: ref - refed- refed

Afirmación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I can ref
you can ref
she can ref
we can ref
you can ref
they can ref 	I can be refing
you can be refing
she can be refing
we can be refing
you can be refing
they can be refing	I can have refed
you can have refed
she can have refed
we can have refed
you can have refed
they can have refed	I can have been refing
you can have been refing
she can have been refing
we can have been refing
you can have been refing
they can have been refing	

Negación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I cannot ref
you cannot ref
she cannot ref
we cannot ref
you cannot ref
they cannot ref 	I cannot be refing
you cannot be refing
she cannot be refing
we cannot be refing
you cannot be refing
they cannot be refing	I cannot have refed
you cannot have refed
she cannot have refed
we cannot have refed
you cannot have refed
they cannot have refed	I cannot have been refing
you cannot have been refing
she cannot have been refing
we cannot have been refing
you cannot have been refing
they cannot have been refing	

Forma interrogativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
can I ref?
can you ref?
can she ref?
can we ref?
can you ref?
can they ref? 	can I be refing?
can you be refing?
can she be refing?
can we be refing?
can you be refing?
can they be refing? 	can I have refed?
can you have refed?
can she have refed?
can we have refed?
can you have refed?
can they have refed? 	can I have been refing?
can you have been refing?
can she have been refing?
can we have been refing?
can you have been refing?
can they have been refing? 	

Forma interro-negativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
can I not ref?
can you not ref?
can she not ref?
can we not ref?
can you not ref?
can they not ref? 	can I not be refing?
can you not be refing?
can she not be refing?
can we not be refing?
can you not be refing?
can they not be refing? 	can I not have refed?
can you not have refed?
can she not have refed?
can we not have refed?
can you not have refed?
can they not have refed? 	can I not have been refing?
can you not have been refing?
can she not have been refing?
can we not have been refing?
can you not have been refing?
can they not have been refing?