I could refute you could refute he could refute we could refute you could refute they could refute
V-ing form
I could be refuting you could be refuting he could be refuting we could be refuting you could be refuting they could be refuting
Perfect
I could have refuted you could have refuted he could have refuted we could have refuted you could have refuted they could have refuted
V-ing perfect
I could have been refuting you could have been refuting he could have been refuting we could have been refuting you could have been refuting they could have been refuting
Negation
Simple form
I could not refute you could not refute he could not refute we could not refute you could not refute they could not refute
V-ing form
I could not be refuting you could not be refuting he could not be refuting we could not be refuting you could not be refuting they could not be refuting
Perfect
I could not have refuted you could not have refuted he could not have refuted we could not have refuted you could not have refuted they could not have refuted
V-ing perfect
I could not have been refuting you could not have been refuting he could not have been refuting we could not have been refuting you could not have been refuting they could not have been refuting
Interrogative form
Simple form
could I refute? could you refute? could he refute? could we refute? could you refute? could they refute?
V-ing form
could I be refuting? could you be refuting? could he be refuting? could we be refuting? could you be refuting? could they be refuting?
Perfect
could I have refuted? could you have refuted? could he have refuted? could we have refuted? could you have refuted? could they have refuted?
V-ing perfect
could I have been refuting? could you have been refuting? could he have been refuting? could we have been refuting? could you have been refuting? could they have been refuting?
Interro-negative form
Simple form
could I not refute? could you not refute? could he not refute? could we not refute? could you not refute? could they not refute?
V-ing form
could I not be refuting? could you not be refuting? could he not be refuting? could we not be refuting? could you not be refuting? could they not be refuting?
Perfect
could I not have refuted? could you not have refuted? could he not have refuted? could we not have refuted? could you not have refuted? could they not have refuted?
V-ing perfect
could I not have been refuting? could you not have been refuting? could he not have been refuting? could we not have been refuting? could you not have been refuting? could they not have been refuting?