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