English verb conjugation
MUST PREVENT

Regular verb: prevent - prevented - prevented

Affirmation

Simple form	V-ing form
I must prevent you must prevent he must prevent we must prevent you must prevent they must prevent	I must be preventing you must be preventing he must be preventing we must be preventing you must be preventing they must be preventing
Perfect	V-ing perfect
I must have prevented you must have prevented he must have prevented we must have prevented you must have prevented they must have prevented	I must have been preventing you must have been preventing he must have been preventing we must have been preventing you must have been preventing they must have been preventing

Negation

Simple form	V-ing form
I mustn't prevent you mustn't prevent he mustn't prevent we mustn't prevent you mustn't prevent they mustn't prevent	I mustn't be preventing you mustn't be preventing he mustn't be preventing we mustn't be preventing you mustn't be preventing they mustn't be preventing
Perfect	V-ing perfect
I mustn't have prevented you mustn't have prevented he mustn't have prevented we mustn't have prevented you mustn't have prevented they mustn't have prevented	I mustn't have been preventing you mustn't have been preventing he mustn't have been preventing we mustn't have been preventing you mustn't have been preventing they mustn't have been preventing

Interrogative form

Simple form	V-ing form
must I prevent? must you prevent? must he prevent? must we prevent? must you prevent? must they prevent?	must I be preventing? must you be preventing? must he be preventing? must we be preventing? must you be preventing? must they be preventing?
Perfect	V-ing perfect
must I have prevented? must you have prevented? must he have prevented? must we have prevented? must you have prevented? must they have prevented?	must I have been preventing? must you have been preventing? must he have been preventing? must we have been preventing? must you have been preventing? must they have been preventing?

Interro-negative form

Simple form	V-ing form
mustn't I prevent? mustn't you prevent? mustn't he prevent? mustn't we prevent? mustn't you prevent? mustn't they prevent?	mustn't I be preventing? mustn't you be preventing? mustn't he be preventing? mustn't we be preventing? mustn't you be preventing? mustn't they be preventing?
Perfect	V-ing perfect
mustn't I have prevented? mustn't you have prevented? mustn't he have prevented? mustn't we have prevented? mustn't you have prevented? mustn't they have prevented?	mustn't I have been preventing? mustn't you have been preventing? mustn't he have been preventing? mustn't we have been preventing? mustn't you have been preventing? mustn't they have been preventing?