I could den you could den she could den we could den you could den they could den
V-ing form
I could be dening you could be dening she could be dening we could be dening you could be dening they could be dening
Perfect
I could have dened you could have dened she could have dened we could have dened you could have dened they could have dened
V-ing perfect
I could have been dening you could have been dening she could have been dening we could have been dening you could have been dening they could have been dening
Negation
Simple form
I could not den you could not den she could not den we could not den you could not den they could not den
V-ing form
I could not be dening you could not be dening she could not be dening we could not be dening you could not be dening they could not be dening
Perfect
I could not have dened you could not have dened she could not have dened we could not have dened you could not have dened they could not have dened
V-ing perfect
I could not have been dening you could not have been dening she could not have been dening we could not have been dening you could not have been dening they could not have been dening
Interrogative form
Simple form
could I den? could you den? could she den? could we den? could you den? could they den?
V-ing form
could I be dening? could you be dening? could she be dening? could we be dening? could you be dening? could they be dening?
Perfect
could I have dened? could you have dened? could she have dened? could we have dened? could you have dened? could they have dened?
V-ing perfect
could I have been dening? could you have been dening? could she have been dening? could we have been dening? could you have been dening? could they have been dening?
Interro-negative form
Simple form
could I not den? could you not den? could she not den? could we not den? could you not den? could they not den?
V-ing form
could I not be dening? could you not be dening? could she not be dening? could we not be dening? could you not be dening? could they not be dening?
Perfect
could I not have dened? could you not have dened? could she not have dened? could we not have dened? could you not have dened? could they not have dened?
V-ing perfect
could I not have been dening? could you not have been dening? could she not have been dening? could we not have been dening? could you not have been dening? could they not have been dening?