I could duel you could duel she could duel we could duel you could duel they could duel
V-ing form
I could be dueling you could be dueling she could be dueling we could be dueling you could be dueling they could be dueling
Perfect
I could have dueled you could have dueled she could have dueled we could have dueled you could have dueled they could have dueled
V-ing perfect
I could have been dueling you could have been dueling she could have been dueling we could have been dueling you could have been dueling they could have been dueling
Negation
Simple form
I could not duel you could not duel she could not duel we could not duel you could not duel they could not duel
V-ing form
I could not be dueling you could not be dueling she could not be dueling we could not be dueling you could not be dueling they could not be dueling
Perfect
I could not have dueled you could not have dueled she could not have dueled we could not have dueled you could not have dueled they could not have dueled
V-ing perfect
I could not have been dueling you could not have been dueling she could not have been dueling we could not have been dueling you could not have been dueling they could not have been dueling
Interrogative form
Simple form
could I duel? could you duel? could she duel? could we duel? could you duel? could they duel?
V-ing form
could I be dueling? could you be dueling? could she be dueling? could we be dueling? could you be dueling? could they be dueling?
Perfect
could I have dueled? could you have dueled? could she have dueled? could we have dueled? could you have dueled? could they have dueled?
V-ing perfect
could I have been dueling? could you have been dueling? could she have been dueling? could we have been dueling? could you have been dueling? could they have been dueling?
Interro-negative form
Simple form
could I not duel? could you not duel? could she not duel? could we not duel? could you not duel? could they not duel?
V-ing form
could I not be dueling? could you not be dueling? could she not be dueling? could we not be dueling? could you not be dueling? could they not be dueling?
Perfect
could I not have dueled? could you not have dueled? could she not have dueled? could we not have dueled? could you not have dueled? could they not have dueled?
V-ing perfect
could I not have been dueling? could you not have been dueling? could she not have been dueling? could we not have been dueling? could you not have been dueling? could they not have been dueling?