could refute
Regular verb: refute - refuted- refuted

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could refute
you could refute
he could refute
we could refute
you could refute
they could refute 	I could be refuting
you could be refuting
he could be refuting
we could be refuting
you could be refuting
they could be refuting	I could have refuted
you could have refuted
he could have refuted
we could have refuted
you could have refuted
they could have refuted	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 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't refute
you couldn't refute
he couldn't refute
we couldn't refute
you couldn't refute
they couldn't refute 	I couldn't be refuting
you couldn't be refuting
he couldn't be refuting
we couldn't be refuting
you couldn't be refuting
they couldn't be refuting	I couldn't have refuted
you couldn't have refuted
he couldn't have refuted
we couldn't have refuted
you couldn't have refuted
they couldn't have refuted	I couldn't have been refuting
you couldn't have been refuting
he couldn't have been refuting
we couldn't have been refuting
you couldn't have been refuting
they couldn't have been refuting	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I refute?
could you refute?
could he refute?
could we refute?
could you refute?
could they refute? 	could I be refuting?
could you be refuting?
could he be refuting?
could we be refuting?
could you be refuting?
could they be refuting? 	could I have refuted?
could you have refuted?
could he have refuted?
could we have refuted?
could you have refuted?
could they have refuted? 	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 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I refute?
couldn't you refute?
couldn't he refute?
couldn't we refute?
couldn't you refute?
couldn't they refute? 	couldn't I be refuting?
couldn't you be refuting?
couldn't he be refuting?
couldn't we be refuting?
couldn't you be refuting?
couldn't they be refuting? 	couldn't I have refuted?
couldn't you have refuted?
couldn't he have refuted?
couldn't we have refuted?
couldn't you have refuted?
couldn't they have refuted? 	couldn't I have been refuting?
couldn't you have been refuting?
couldn't he have been refuting?
couldn't we have been refuting?
couldn't you have been refuting?
couldn't they have been refuting?