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