could jack
Regular verb: jack - jacked- jacked

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could jack
you could jack
he could jack
we could jack
you could jack
they could jack 	I could be jacking
you could be jacking
he could be jacking
we could be jacking
you could be jacking
they could be jacking	I could have jacked
you could have jacked
he could have jacked
we could have jacked
you could have jacked
they could have jacked	I could have been jacking
you could have been jacking
he could have been jacking
we could have been jacking
you could have been jacking
they could have been jacking	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could not jack
you could not jack
he could not jack
we could not jack
you could not jack
they could not jack 	I could not be jacking
you could not be jacking
he could not be jacking
we could not be jacking
you could not be jacking
they could not be jacking	I could not have jacked
you could not have jacked
he could not have jacked
we could not have jacked
you could not have jacked
they could not have jacked	I could not have been jacking
you could not have been jacking
he could not have been jacking
we could not have been jacking
you could not have been jacking
they could not have been jacking	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I jack?
could you jack?
could he jack?
could we jack?
could you jack?
could they jack? 	could I be jacking?
could you be jacking?
could he be jacking?
could we be jacking?
could you be jacking?
could they be jacking? 	could I have jacked?
could you have jacked?
could he have jacked?
could we have jacked?
could you have jacked?
could they have jacked? 	could I have been jacking?
could you have been jacking?
could he have been jacking?
could we have been jacking?
could you have been jacking?
could they have been jacking? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I not jack?
could you not jack?
could he not jack?
could we not jack?
could you not jack?
could they not jack? 	could I not be jacking?
could you not be jacking?
could he not be jacking?
could we not be jacking?
could you not be jacking?
could they not be jacking? 	could I not have jacked?
could you not have jacked?
could he not have jacked?
could we not have jacked?
could you not have jacked?
could they not have jacked? 	could I not have been jacking?
could you not have been jacking?
could he not have been jacking?
could we not have been jacking?
could you not have been jacking?
could they not have been jacking?