I could contest you could contest he could contest we could contest you could contest they could contest
V-ing form
I could be contesting you could be contesting he could be contesting we could be contesting you could be contesting they could be contesting
Perfect
I could have contested you could have contested he could have contested we could have contested you could have contested they could have contested
V-ing perfect
I could have been contesting you could have been contesting he could have been contesting we could have been contesting you could have been contesting they could have been contesting
Negation
Simple form
I could not contest you could not contest he could not contest we could not contest you could not contest they could not contest
V-ing form
I could not be contesting you could not be contesting he could not be contesting we could not be contesting you could not be contesting they could not be contesting
Perfect
I could not have contested you could not have contested he could not have contested we could not have contested you could not have contested they could not have contested
V-ing perfect
I could not have been contesting you could not have been contesting he could not have been contesting we could not have been contesting you could not have been contesting they could not have been contesting
Interrogative form
Simple form
could I contest? could you contest? could he contest? could we contest? could you contest? could they contest?
V-ing form
could I be contesting? could you be contesting? could he be contesting? could we be contesting? could you be contesting? could they be contesting?
Perfect
could I have contested? could you have contested? could he have contested? could we have contested? could you have contested? could they have contested?
V-ing perfect
could I have been contesting? could you have been contesting? could he have been contesting? could we have been contesting? could you have been contesting? could they have been contesting?
Interro-negative form
Simple form
could I not contest? could you not contest? could he not contest? could we not contest? could you not contest? could they not contest?
V-ing form
could I not be contesting? could you not be contesting? could he not be contesting? could we not be contesting? could you not be contesting? could they not be contesting?
Perfect
could I not have contested? could you not have contested? could he not have contested? could we not have contested? could you not have contested? could they not have contested?
V-ing perfect
could I not have been contesting? could you not have been contesting? could he not have been contesting? could we not have been contesting? could you not have been contesting? could they not have been contesting?