Warning, this verb may not exist. Conjugation is given as example.
Affirmation
Simple form
I could exert use you could exert use he could exert use we could exert use you could exert use they could exert use
V-ing form
I could be exert using you could be exert using he could be exert using we could be exert using you could be exert using they could be exert using
Perfect
I could have exert used you could have exert used he could have exert used we could have exert used you could have exert used they could have exert used
V-ing perfect
I could have been exert using you could have been exert using he could have been exert using we could have been exert using you could have been exert using they could have been exert using
Negation
Simple form
I could not exert use you could not exert use he could not exert use we could not exert use you could not exert use they could not exert use
V-ing form
I could not be exert using you could not be exert using he could not be exert using we could not be exert using you could not be exert using they could not be exert using
Perfect
I could not have exert used you could not have exert used he could not have exert used we could not have exert used you could not have exert used they could not have exert used
V-ing perfect
I could not have been exert using you could not have been exert using he could not have been exert using we could not have been exert using you could not have been exert using they could not have been exert using
Interrogative form
Simple form
could I exert use? could you exert use? could he exert use? could we exert use? could you exert use? could they exert use?
V-ing form
could I be exert using? could you be exert using? could he be exert using? could we be exert using? could you be exert using? could they be exert using?
Perfect
could I have exert used? could you have exert used? could he have exert used? could we have exert used? could you have exert used? could they have exert used?
V-ing perfect
could I have been exert using? could you have been exert using? could he have been exert using? could we have been exert using? could you have been exert using? could they have been exert using?
Interro-negative form
Simple form
could I not exert use? could you not exert use? could he not exert use? could we not exert use? could you not exert use? could they not exert use?
V-ing form
could I not be exert using? could you not be exert using? could he not be exert using? could we not be exert using? could you not be exert using? could they not be exert using?
Perfect
could I not have exert used? could you not have exert used? could he not have exert used? could we not have exert used? could you not have exert used? could they not have exert used?
V-ing perfect
could I not have been exert using? could you not have been exert using? could he not have been exert using? could we not have been exert using? could you not have been exert using? could they not have been exert using?