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