English verb conjugation
COULD USE

Regular verb: use - used - used

Affirmation

Simple form	V-ing form
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
Perfect	V-ing perfect
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
I could not use you could not use he could not use we could not use you could not use they could not use	I could not be using you could not be using he could not be using we could not be using you could not be using they could not be using
Perfect	V-ing perfect
I could not have used you could not have used he could not have used we could not have used you could not have used they could not have used	I could not have been using you could not have been using he could not have been using we could not have been using you could not have been using they could not have been using

Interrogative form

Simple form	V-ing form
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?
Perfect	V-ing perfect
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
could I not use? could you not use? could he not use? could we not use? could you not use? could they not use?	could I not be using? could you not be using? could he not be using? could we not be using? could you not be using? could they not be using?
Perfect	V-ing perfect
could I not have used? could you not have used? could he not have used? could we not have used? could you not have used? could they not have used?	could I not have been using? could you not have been using? could he not have been using? could we not have been using? could you not have been using? could they not have been using?