I could prevail you could prevail he could prevail we could prevail you could prevail they could prevail
V-ing form
I could be prevailing you could be prevailing he could be prevailing we could be prevailing you could be prevailing they could be prevailing
Perfect
I could have prevailed you could have prevailed he could have prevailed we could have prevailed you could have prevailed they could have prevailed
V-ing perfect
I could have been prevailing you could have been prevailing he could have been prevailing we could have been prevailing you could have been prevailing they could have been prevailing
Negation
Simple form
I could not prevail you could not prevail he could not prevail we could not prevail you could not prevail they could not prevail
V-ing form
I could not be prevailing you could not be prevailing he could not be prevailing we could not be prevailing you could not be prevailing they could not be prevailing
Perfect
I could not have prevailed you could not have prevailed he could not have prevailed we could not have prevailed you could not have prevailed they could not have prevailed
V-ing perfect
I could not have been prevailing you could not have been prevailing he could not have been prevailing we could not have been prevailing you could not have been prevailing they could not have been prevailing
Interrogative form
Simple form
could I prevail? could you prevail? could he prevail? could we prevail? could you prevail? could they prevail?
V-ing form
could I be prevailing? could you be prevailing? could he be prevailing? could we be prevailing? could you be prevailing? could they be prevailing?
Perfect
could I have prevailed? could you have prevailed? could he have prevailed? could we have prevailed? could you have prevailed? could they have prevailed?
V-ing perfect
could I have been prevailing? could you have been prevailing? could he have been prevailing? could we have been prevailing? could you have been prevailing? could they have been prevailing?
Interro-negative form
Simple form
could I not prevail? could you not prevail? could he not prevail? could we not prevail? could you not prevail? could they not prevail?
V-ing form
could I not be prevailing? could you not be prevailing? could he not be prevailing? could we not be prevailing? could you not be prevailing? could they not be prevailing?
Perfect
could I not have prevailed? could you not have prevailed? could he not have prevailed? could we not have prevailed? could you not have prevailed? could they not have prevailed?
V-ing perfect
could I not have been prevailing? could you not have been prevailing? could he not have been prevailing? could we not have been prevailing? could you not have been prevailing? could they not have been prevailing?