English verb conjugation
MUST FIRM

Regular verb: firm - firmed - firmed

Affirmation

Simple form	V-ing form
I must firm you must firm he must firm we must firm you must firm they must firm	I must be firming you must be firming he must be firming we must be firming you must be firming they must be firming
Perfect	V-ing perfect
I must have firmed you must have firmed he must have firmed we must have firmed you must have firmed they must have firmed	I must have been firming you must have been firming he must have been firming we must have been firming you must have been firming they must have been firming

Negation

Simple form	V-ing form
I must not firm you must not firm he must not firm we must not firm you must not firm they must not firm	I must not be firming you must not be firming he must not be firming we must not be firming you must not be firming they must not be firming
Perfect	V-ing perfect
I must not have firmed you must not have firmed he must not have firmed we must not have firmed you must not have firmed they must not have firmed	I must not have been firming you must not have been firming he must not have been firming we must not have been firming you must not have been firming they must not have been firming

Interrogative form

Simple form	V-ing form
must I firm? must you firm? must he firm? must we firm? must you firm? must they firm?	must I be firming? must you be firming? must he be firming? must we be firming? must you be firming? must they be firming?
Perfect	V-ing perfect
must I have firmed? must you have firmed? must he have firmed? must we have firmed? must you have firmed? must they have firmed?	must I have been firming? must you have been firming? must he have been firming? must we have been firming? must you have been firming? must they have been firming?

Interro-negative form

Simple form	V-ing form
must I not firm? must you not firm? must he not firm? must we not firm? must you not firm? must they not firm?	must I not be firming? must you not be firming? must he not be firming? must we not be firming? must you not be firming? must they not be firming?
Perfect	V-ing perfect
must I not have firmed? must you not have firmed? must he not have firmed? must we not have firmed? must you not have firmed? must they not have firmed?	must I not have been firming? must you not have been firming? must he not have been firming? must we not have been firming? must you not have been firming? must they not have been firming?