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 cannot know you cannot know he cannot know we cannot know you cannot know they cannot know
V-ing form
I cannot be knowing you cannot be knowing he cannot be knowing we cannot be knowing you cannot be knowing they cannot be knowing
Perfect
I cannot have known you cannot have known he cannot have known we cannot have known you cannot have known they cannot have known
V-ing perfect
I cannot have been knowing you cannot have been knowing he cannot have been knowing we cannot have been knowing you cannot have been knowing they cannot 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 I not know? can you not know? can he not know? can we not know? can you not know? can they not know?
V-ing form
can I not be knowing? can you not be knowing? can he not be knowing? can we not be knowing? can you not be knowing? can they not be knowing?
Perfect
can I not have known? can you not have known? can he not have known? can we not have known? can you not have known? can they not have known?
V-ing perfect
can I not have been knowing? can you not have been knowing? can he not have been knowing? can we not have been knowing? can you not have been knowing? can they not have been knowing?