English verb conjugation
COULD REF

Regular verb: ref - refed - refed

Affirmation

Simple form	V-ing form
I could ref you could ref he could ref we could ref you could ref they could ref	I could be refing you could be refing he could be refing we could be refing you could be refing they could be refing
Perfect	V-ing perfect
I could have refed you could have refed he could have refed we could have refed you could have refed they could have refed	I could have been refing you could have been refing he could have been refing we could have been refing you could have been refing they could have been refing

Negation

Simple form	V-ing form
I could not ref you could not ref he could not ref we could not ref you could not ref they could not ref	I could not be refing you could not be refing he could not be refing we could not be refing you could not be refing they could not be refing
Perfect	V-ing perfect
I could not have refed you could not have refed he could not have refed we could not have refed you could not have refed they could not have refed	I could not have been refing you could not have been refing he could not have been refing we could not have been refing you could not have been refing they could not have been refing

Interrogative form

Simple form	V-ing form
could I ref? could you ref? could he ref? could we ref? could you ref? could they ref?	could I be refing? could you be refing? could he be refing? could we be refing? could you be refing? could they be refing?
Perfect	V-ing perfect
could I have refed? could you have refed? could he have refed? could we have refed? could you have refed? could they have refed?	could I have been refing? could you have been refing? could he have been refing? could we have been refing? could you have been refing? could they have been refing?

Interro-negative form

Simple form	V-ing form
could I not ref? could you not ref? could he not ref? could we not ref? could you not ref? could they not ref?	could I not be refing? could you not be refing? could he not be refing? could we not be refing? could you not be refing? could they not be refing?
Perfect	V-ing perfect
could I not have refed? could you not have refed? could he not have refed? could we not have refed? could you not have refed? could they not have refed?	could I not have been refing? could you not have been refing? could he not have been refing? could we not have been refing? could you not have been refing? could they not have been refing?