English verb conjugation
MUST EXCUSE

Regular verb: excuse - excused - excused

Affirmation

Simple form	V-ing form
I must excuse you must excuse he must excuse we must excuse you must excuse they must excuse	I must be excusing you must be excusing he must be excusing we must be excusing you must be excusing they must be excusing
Perfect	V-ing perfect
I must have excused you must have excused he must have excused we must have excused you must have excused they must have excused	I must have been excusing you must have been excusing he must have been excusing we must have been excusing you must have been excusing they must have been excusing

Negation

Simple form	V-ing form
I mustn't excuse you mustn't excuse he mustn't excuse we mustn't excuse you mustn't excuse they mustn't excuse	I mustn't be excusing you mustn't be excusing he mustn't be excusing we mustn't be excusing you mustn't be excusing they mustn't be excusing
Perfect	V-ing perfect
I mustn't have excused you mustn't have excused he mustn't have excused we mustn't have excused you mustn't have excused they mustn't have excused	I mustn't have been excusing you mustn't have been excusing he mustn't have been excusing we mustn't have been excusing you mustn't have been excusing they mustn't have been excusing

Interrogative form

Simple form	V-ing form
must I excuse? must you excuse? must he excuse? must we excuse? must you excuse? must they excuse?	must I be excusing? must you be excusing? must he be excusing? must we be excusing? must you be excusing? must they be excusing?
Perfect	V-ing perfect
must I have excused? must you have excused? must he have excused? must we have excused? must you have excused? must they have excused?	must I have been excusing? must you have been excusing? must he have been excusing? must we have been excusing? must you have been excusing? must they have been excusing?

Interro-negative form

Simple form	V-ing form
mustn't I excuse? mustn't you excuse? mustn't he excuse? mustn't we excuse? mustn't you excuse? mustn't they excuse?	mustn't I be excusing? mustn't you be excusing? mustn't he be excusing? mustn't we be excusing? mustn't you be excusing? mustn't they be excusing?
Perfect	V-ing perfect
mustn't I have excused? mustn't you have excused? mustn't he have excused? mustn't we have excused? mustn't you have excused? mustn't they have excused?	mustn't I have been excusing? mustn't you have been excusing? mustn't he have been excusing? mustn't we have been excusing? mustn't you have been excusing? mustn't they have been excusing?