I should prevent you should prevent he should prevent we should prevent you should prevent they should prevent
V-ing form
I should be preventing you should be preventing he should be preventing we should be preventing you should be preventing they should be preventing
Perfect
I should have prevented you should have prevented he should have prevented we should have prevented you should have prevented they should have prevented
V-ing perfect
I should have been preventing you should have been preventing he should have been preventing we should have been preventing you should have been preventing they should have been preventing
Negation
Simple form
I should not prevent you should not prevent he should not prevent we should not prevent you should not prevent they should not prevent
V-ing form
I should not be preventing you should not be preventing he should not be preventing we should not be preventing you should not be preventing they should not be preventing
Perfect
I should not have prevented you should not have prevented he should not have prevented we should not have prevented you should not have prevented they should not have prevented
V-ing perfect
I should not have been preventing you should not have been preventing he should not have been preventing we should not have been preventing you should not have been preventing they should not have been preventing
Interrogative form
Simple form
should I prevent? should you prevent? should he prevent? should we prevent? should you prevent? should they prevent?
V-ing form
should I be preventing? should you be preventing? should he be preventing? should we be preventing? should you be preventing? should they be preventing?
Perfect
should I have prevented? should you have prevented? should he have prevented? should we have prevented? should you have prevented? should they have prevented?
V-ing perfect
should I have been preventing? should you have been preventing? should he have been preventing? should we have been preventing? should you have been preventing? should they have been preventing?
Interro-negative form
Simple form
should I not prevent? should you not prevent? should he not prevent? should we not prevent? should you not prevent? should they not prevent?
V-ing form
should I not be preventing? should you not be preventing? should he not be preventing? should we not be preventing? should you not be preventing? should they not be preventing?
Perfect
should I not have prevented? should you not have prevented? should he not have prevented? should we not have prevented? should you not have prevented? should they not have prevented?
V-ing perfect
should I not have been preventing? should you not have been preventing? should he not have been preventing? should we not have been preventing? should you not have been preventing? should they not have been preventing?