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