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