I could curl you could curl she could curl we could curl you could curl they could curl
V-ing form
I could be curling you could be curling she could be curling we could be curling you could be curling they could be curling
Perfect
I could have curled you could have curled she could have curled we could have curled you could have curled they could have curled
V-ing perfect
I could have been curling you could have been curling she could have been curling we could have been curling you could have been curling they could have been curling
Negation
Simple form
I couldn't curl you couldn't curl she couldn't curl we couldn't curl you couldn't curl they couldn't curl
V-ing form
I couldn't be curling you couldn't be curling she couldn't be curling we couldn't be curling you couldn't be curling they couldn't be curling
Perfect
I couldn't have curled you couldn't have curled she couldn't have curled we couldn't have curled you couldn't have curled they couldn't have curled
V-ing perfect
I couldn't have been curling you couldn't have been curling she couldn't have been curling we couldn't have been curling you couldn't have been curling they couldn't have been curling
Interrogative form
Simple form
could I curl? could you curl? could she curl? could we curl? could you curl? could they curl?
V-ing form
could I be curling? could you be curling? could she be curling? could we be curling? could you be curling? could they be curling?
Perfect
could I have curled? could you have curled? could she have curled? could we have curled? could you have curled? could they have curled?
V-ing perfect
could I have been curling? could you have been curling? could she have been curling? could we have been curling? could you have been curling? could they have been curling?
Interro-negative form
Simple form
couldn't I curl? couldn't you curl? couldn't she curl? couldn't we curl? couldn't you curl? couldn't they curl?
V-ing form
couldn't I be curling? couldn't you be curling? couldn't she be curling? couldn't we be curling? couldn't you be curling? couldn't they be curling?
Perfect
couldn't I have curled? couldn't you have curled? couldn't she have curled? couldn't we have curled? couldn't you have curled? couldn't they have curled?
V-ing perfect
couldn't I have been curling? couldn't you have been curling? couldn't she have been curling? couldn't we have been curling? couldn't you have been curling? couldn't they have been curling?