ought to prevent
Regular verb: prevent - prevented- prevented

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I ought to prevent
you ought to prevent
she ought to prevent
we ought to prevent
you ought to prevent
they ought to prevent 	I ought to be preventing
you ought to be preventing
she ought to be preventing
we ought to be preventing
you ought to be preventing
they ought to be preventing	I ought to have prevented
you ought to have prevented
she ought to have prevented
we ought to have prevented
you ought to have prevented
they ought to have prevented	I ought to have been preventing
you ought to have been preventing
she ought to have been preventing
we ought to have been preventing
you ought to have been preventing
they ought to have been preventing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I ought not to prevent
you ought not to prevent
she ought not to prevent
we ought not to prevent
you ought not to prevent
they ought not to prevent 	I ought not to preventing
you ought not to preventing
she ought not to preventing
we ought not to preventing
you ought not to preventing
they ought not to preventing	I ought not to have prevented
you ought not to have prevented
she ought not to have prevented
we ought not to have prevented
you ought not to have prevented
they ought not to have prevented	I ought not to have been preventing
you ought not to have been preventing
she ought not to have been preventing
we ought not to have been preventing
you ought not to have been preventing
they ought not to have been preventing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
ought to I prevent?
ought to you prevent?
ought to she prevent?
ought to we prevent?
ought to you prevent?
ought to they prevent? 	ought to I be preventing?
ought to you be preventing?
ought to she be preventing?
ought to we be preventing?
ought to you be preventing?
ought to they be preventing? 	ought to I have prevented?
ought to you have prevented?
ought to she have prevented?
ought to we have prevented?
ought to you have prevented?
ought to they have prevented? 	ought to I have been preventing?
ought to you have been preventing?
ought to she have been preventing?
ought to we have been preventing?
ought to you have been preventing?
ought to they have been preventing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
ought I not to prevent?
ought you not to prevent?
ought she not to prevent?
ought we not to prevent?
ought you not to prevent?
ought they not to prevent? 	ought I not to be preventing?
ought you not to be preventing?
ought she not to be preventing?
ought we not to be preventing?
ought you not to be preventing?
ought they not to be preventing? 	ought I not to have prevented?
ought you not to have prevented?
ought she not to have prevented?
ought we not to have prevented?
ought you not to have prevented?
ought they not to have prevented? 	ought I not to have been preventing?
ought you not to have been preventing?
ought she not to have been preventing?
ought we not to have been preventing?
ought you not to have been preventing?
ought they not to have been preventing?