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