could know
Irregular verb: know - knew- known

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