English verb conjugation
MUST UNDERUSE

Regular verb: underuse - underused - underused

Affirmation

Simple form	V-ing form
I must underuse you must underuse he must underuse we must underuse you must underuse they must underuse	I must be underusing you must be underusing he must be underusing we must be underusing you must be underusing they must be underusing
Perfect	V-ing perfect
I must have underused you must have underused he must have underused we must have underused you must have underused they must have underused	I must have been underusing you must have been underusing he must have been underusing we must have been underusing you must have been underusing they must have been underusing

Negation

Simple form	V-ing form
I must not underuse you must not underuse he must not underuse we must not underuse you must not underuse they must not underuse	I must not be underusing you must not be underusing he must not be underusing we must not be underusing you must not be underusing they must not be underusing
Perfect	V-ing perfect
I must not have underused you must not have underused he must not have underused we must not have underused you must not have underused they must not have underused	I must not have been underusing you must not have been underusing he must not have been underusing we must not have been underusing you must not have been underusing they must not have been underusing

Interrogative form

Simple form	V-ing form
must I underuse? must you underuse? must he underuse? must we underuse? must you underuse? must they underuse?	must I be underusing? must you be underusing? must he be underusing? must we be underusing? must you be underusing? must they be underusing?
Perfect	V-ing perfect
must I have underused? must you have underused? must he have underused? must we have underused? must you have underused? must they have underused?	must I have been underusing? must you have been underusing? must he have been underusing? must we have been underusing? must you have been underusing? must they have been underusing?

Interro-negative form

Simple form	V-ing form
must I not underuse? must you not underuse? must he not underuse? must we not underuse? must you not underuse? must they not underuse?	must I not be underusing? must you not be underusing? must he not be underusing? must we not be underusing? must you not be underusing? must they not be underusing?
Perfect	V-ing perfect
must I not have underused? must you not have underused? must he not have underused? must we not have underused? must you not have underused? must they not have underused?	must I not have been underusing? must you not have been underusing? must he not have been underusing? must we not have been underusing? must you not have been underusing? must they not have been underusing?