I could refer you could refer she could refer we could refer you could refer they could refer
Forma con V-ing
I could be referring you could be referring she could be referring we could be referring you could be referring they could be referring
Perfecto
I could have referred you could have referred she could have referred we could have referred you could have referred they could have referred
Perfecto con V-ing
I could have been referring you could have been referring she could have been referring we could have been referring you could have been referring they could have been referring
Negación
Forma simple
I could not refer you could not refer she could not refer we could not refer you could not refer they could not refer
Forma con V-ing
I could not be referring you could not be referring she could not be referring we could not be referring you could not be referring they could not be referring
Perfecto
I could not have referred you could not have referred she could not have referred we could not have referred you could not have referred they could not have referred
Perfecto con V-ing
I could not have been referring you could not have been referring she could not have been referring we could not have been referring you could not have been referring they could not have been referring
Forma interrogativa
Forma simple
could I refer? could you refer? could she refer? could we refer? could you refer? could they refer?
Forma con V-ing
could I be referring? could you be referring? could she be referring? could we be referring? could you be referring? could they be referring?
Perfecto
could I have referred? could you have referred? could she have referred? could we have referred? could you have referred? could they have referred?
Perfecto con V-ing
could I have been referring? could you have been referring? could she have been referring? could we have been referring? could you have been referring? could they have been referring?
Forma interro-negativa
Forma simple
could I not refer? could you not refer? could she not refer? could we not refer? could you not refer? could they not refer?
Forma con V-ing
could I not be referring? could you not be referring? could she not be referring? could we not be referring? could you not be referring? could they not be referring?
Perfecto
could I not have referred? could you not have referred? could she not have referred? could we not have referred? could you not have referred? could they not have referred?
Perfecto con V-ing
could I not have been referring? could you not have been referring? could she not have been referring? could we not have been referring? could you not have been referring? could they not have been referring?