English verb conjugation
COULD KNOW

Irregular verb: know - knew - known

Affirmation

Simple form	V-ing form
I could know you could know he could know we could know you could know they could know	I could be knowing you could be knowing he could be knowing we could be knowing you could be knowing they could be knowing
Perfect	V-ing perfect
I could have known you could have known he could have known we could have known you could have known they could have known	I could have been knowing you could have been knowing he could have been knowing we could have been knowing you could have been knowing they could have been knowing

Negation

Simple form	V-ing form
I couldn't know you couldn't know he couldn't know we couldn't know you couldn't know they couldn't know	I couldn't be knowing you couldn't be knowing he couldn't be knowing we couldn't be knowing you couldn't be knowing they couldn't be knowing
Perfect	V-ing perfect
I couldn't have known you couldn't have known he couldn't have known we couldn't have known you couldn't have known they couldn't have known	I couldn't have been knowing you couldn't have been knowing he couldn't have been knowing we couldn't have been knowing you couldn't have been knowing they couldn't have been knowing

Interrogative form

Simple form	V-ing form
could I know? could you know? could he know? could we know? could you know? could they know?	could I be knowing? could you be knowing? could he be knowing? could we be knowing? could you be knowing? could they be knowing?
Perfect	V-ing perfect
could I have known? could you have known? could he have known? could we have known? could you have known? could they have known?	could I have been knowing? could you have been knowing? could he have been knowing? could we have been knowing? could you have been knowing? could they have been knowing?

Interro-negative form

Simple form	V-ing form
couldn't I know? couldn't you know? couldn't he know? couldn't we know? couldn't you know? couldn't they know?	couldn't I be knowing? couldn't you be knowing? couldn't he be knowing? couldn't we be knowing? couldn't you be knowing? couldn't they be knowing?
Perfect	V-ing perfect
couldn't I have known? couldn't you have known? couldn't he have known? couldn't we have known? couldn't you have known? couldn't they have known?	couldn't I have been knowing? couldn't you have been knowing? couldn't he have been knowing? couldn't we have been knowing? couldn't you have been knowing? couldn't they have been knowing?