could further
Regular verb: further - furthered- furthered

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could further
you could further
she could further
we could further
you could further
they could further 	I could be furthering
you could be furthering
she could be furthering
we could be furthering
you could be furthering
they could be furthering	I could have furthered
you could have furthered
she could have furthered
we could have furthered
you could have furthered
they could have furthered	I could have been furthering
you could have been furthering
she could have been furthering
we could have been furthering
you could have been furthering
they could have been furthering	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't further
you couldn't further
she couldn't further
we couldn't further
you couldn't further
they couldn't further 	I couldn't be furthering
you couldn't be furthering
she couldn't be furthering
we couldn't be furthering
you couldn't be furthering
they couldn't be furthering	I couldn't have furthered
you couldn't have furthered
she couldn't have furthered
we couldn't have furthered
you couldn't have furthered
they couldn't have furthered	I couldn't have been furthering
you couldn't have been furthering
she couldn't have been furthering
we couldn't have been furthering
you couldn't have been furthering
they couldn't have been furthering	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I further?
could you further?
could she further?
could we further?
could you further?
could they further? 	could I be furthering?
could you be furthering?
could she be furthering?
could we be furthering?
could you be furthering?
could they be furthering? 	could I have furthered?
could you have furthered?
could she have furthered?
could we have furthered?
could you have furthered?
could they have furthered? 	could I have been furthering?
could you have been furthering?
could she have been furthering?
could we have been furthering?
could you have been furthering?
could they have been furthering? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I further?
couldn't you further?
couldn't she further?
couldn't we further?
couldn't you further?
couldn't they further? 	couldn't I be furthering?
couldn't you be furthering?
couldn't she be furthering?
couldn't we be furthering?
couldn't you be furthering?
couldn't they be furthering? 	couldn't I have furthered?
couldn't you have furthered?
couldn't she have furthered?
couldn't we have furthered?
couldn't you have furthered?
couldn't they have furthered? 	couldn't I have been furthering?
couldn't you have been furthering?
couldn't she have been furthering?
couldn't we have been furthering?
couldn't you have been furthering?
couldn't they have been furthering?