English verb conjugation
COULD REFER

Regular verb: refer - referred - referred

Affirmation

Simple form	V-ing form
I could refer you could refer he could refer we could refer you could refer they could refer	I could be referring you could be referring he could be referring we could be referring you could be referring they could be referring
Perfect	V-ing perfect
I could have referred you could have referred he could have referred we could have referred you could have referred they could have referred	I could have been referring you could have been referring he could have been referring we could have been referring you could have been referring they could have been referring

Negation

Simple form	V-ing form
I could not refer you could not refer he could not refer we could not refer you could not refer they could not refer	I could not be referring you could not be referring he could not be referring we could not be referring you could not be referring they could not be referring
Perfect	V-ing perfect
I could not have referred you could not have referred he could not have referred we could not have referred you could not have referred they could not have referred	I could not have been referring you could not have been referring he could not have been referring we could not have been referring you could not have been referring they could not have been referring

Interrogative form

Simple form	V-ing form
could I refer? could you refer? could he refer? could we refer? could you refer? could they refer?	could I be referring? could you be referring? could he be referring? could we be referring? could you be referring? could they be referring?
Perfect	V-ing perfect
could I have referred? could you have referred? could he have referred? could we have referred? could you have referred? could they have referred?	could I have been referring? could you have been referring? could he have been referring? could we have been referring? could you have been referring? could they have been referring?

Interro-negative form

Simple form	V-ing form
could I not refer? could you not refer? could he not refer? could we not refer? could you not refer? could they not refer?	could I not be referring? could you not be referring? could he not be referring? could we not be referring? could you not be referring? could they not be referring?
Perfect	V-ing perfect
could I not have referred? could you not have referred? could he not have referred? could we not have referred? could you not have referred? could they not have referred?	could I not have been referring? could you not have been referring? could he not have been referring? could we not have been referring? could you not have been referring? could they not have been referring?