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