I could refuse you could refuse he could refuse we could refuse you could refuse they could refuse
V-ing form
I could be refusing you could be refusing he could be refusing we could be refusing you could be refusing they could be refusing
Perfect
I could have refused you could have refused he could have refused we could have refused you could have refused they could have refused
V-ing perfect
I could have been refusing you could have been refusing he could have been refusing we could have been refusing you could have been refusing they could have been refusing
Negation
Simple form
I couldn't refuse you couldn't refuse he couldn't refuse we couldn't refuse you couldn't refuse they couldn't refuse
V-ing form
I couldn't be refusing you couldn't be refusing he couldn't be refusing we couldn't be refusing you couldn't be refusing they couldn't be refusing
Perfect
I couldn't have refused you couldn't have refused he couldn't have refused we couldn't have refused you couldn't have refused they couldn't have refused
V-ing perfect
I couldn't have been refusing you couldn't have been refusing he couldn't have been refusing we couldn't have been refusing you couldn't have been refusing they couldn't have been refusing
Interrogative form
Simple form
could I refuse? could you refuse? could he refuse? could we refuse? could you refuse? could they refuse?
V-ing form
could I be refusing? could you be refusing? could he be refusing? could we be refusing? could you be refusing? could they be refusing?
Perfect
could I have refused? could you have refused? could he have refused? could we have refused? could you have refused? could they have refused?
V-ing perfect
could I have been refusing? could you have been refusing? could he have been refusing? could we have been refusing? could you have been refusing? could they have been refusing?
Interro-negative form
Simple form
couldn't I refuse? couldn't you refuse? couldn't he refuse? couldn't we refuse? couldn't you refuse? couldn't they refuse?
V-ing form
couldn't I be refusing? couldn't you be refusing? couldn't he be refusing? couldn't we be refusing? couldn't you be refusing? couldn't they be refusing?
Perfect
couldn't I have refused? couldn't you have refused? couldn't he have refused? couldn't we have refused? couldn't you have refused? couldn't they have refused?
V-ing perfect
couldn't I have been refusing? couldn't you have been refusing? couldn't he have been refusing? couldn't we have been refusing? couldn't you have been refusing? couldn't they have been refusing?