I can know you can know he can know we can know you can know they can know
V-ing form
I can be knowing you can be knowing he can be knowing we can be knowing you can be knowing they can be knowing
Perfect
I can have known you can have known he can have known we can have known you can have known they can have known
V-ing perfect
I can have been knowing you can have been knowing he can have been knowing we can have been knowing you can have been knowing they can have been knowing
Negation
Simple form
I can't know you can't know he can't know we can't know you can't know they can't know
V-ing form
I can't be knowing you can't be knowing he can't be knowing we can't be knowing you can't be knowing they can't be knowing
Perfect
I can't have known you can't have known he can't have known we can't have known you can't have known they can't have known
V-ing perfect
I can't have been knowing you can't have been knowing he can't have been knowing we can't have been knowing you can't have been knowing they can't have been knowing
Interrogative form
Simple form
can I know? can you know? can he know? can we know? can you know? can they know?
V-ing form
can I be knowing? can you be knowing? can he be knowing? can we be knowing? can you be knowing? can they be knowing?
Perfect
can I have known? can you have known? can he have known? can we have known? can you have known? can they have known?
V-ing perfect
can I have been knowing? can you have been knowing? can he have been knowing? can we have been knowing? can you have been knowing? can they have been knowing?
Interro-negative form
Simple form
can't I know? can't you know? can't he know? can't we know? can't you know? can't they know?
V-ing form
can't I be knowing? can't you be knowing? can't he be knowing? can't we be knowing? can't you be knowing? can't they be knowing?
Perfect
can't I have known? can't you have known? can't he have known? can't we have known? can't you have known? can't they have known?
V-ing perfect
can't I have been knowing? can't you have been knowing? can't he have been knowing? can't we have been knowing? can't you have been knowing? can't they have been knowing?