could use
Regular verb: use - used- used

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could use
you could use
he could use
we could use
you could use
they could use 	I could be using
you could be using
he could be using
we could be using
you could be using
they could be using	I could have used
you could have used
he could have used
we could have used
you could have used
they could have used	I could have been using
you could have been using
he could have been using
we could have been using
you could have been using
they could have been using	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't use
you couldn't use
he couldn't use
we couldn't use
you couldn't use
they couldn't use 	I couldn't be using
you couldn't be using
he couldn't be using
we couldn't be using
you couldn't be using
they couldn't be using	I couldn't have used
you couldn't have used
he couldn't have used
we couldn't have used
you couldn't have used
they couldn't have used	I couldn't have been using
you couldn't have been using
he couldn't have been using
we couldn't have been using
you couldn't have been using
they couldn't have been using	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I use?
could you use?
could he use?
could we use?
could you use?
could they use? 	could I be using?
could you be using?
could he be using?
could we be using?
could you be using?
could they be using? 	could I have used?
could you have used?
could he have used?
could we have used?
could you have used?
could they have used? 	could I have been using?
could you have been using?
could he have been using?
could we have been using?
could you have been using?
could they have been using? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I use?
couldn't you use?
couldn't he use?
couldn't we use?
couldn't you use?
couldn't they use? 	couldn't I be using?
couldn't you be using?
couldn't he be using?
couldn't we be using?
couldn't you be using?
couldn't they be using? 	couldn't I have used?
couldn't you have used?
couldn't he have used?
couldn't we have used?
couldn't you have used?
couldn't they have used? 	couldn't I have been using?
couldn't you have been using?
couldn't he have been using?
couldn't we have been using?
couldn't you have been using?
couldn't they have been using?