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 mustn't firm you mustn't firm he mustn't firm we mustn't firm you mustn't firm they mustn't firm	I mustn't be firming you mustn't be firming he mustn't be firming we mustn't be firming you mustn't be firming they mustn't be firming
Perfect	V-ing perfect
I mustn't have firmed you mustn't have firmed he mustn't have firmed we mustn't have firmed you mustn't have firmed they mustn't have firmed	I mustn't have been firming you mustn't have been firming he mustn't have been firming we mustn't have been firming you mustn't have been firming they mustn't 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
mustn't I firm? mustn't you firm? mustn't he firm? mustn't we firm? mustn't you firm? mustn't they firm?	mustn't I be firming? mustn't you be firming? mustn't he be firming? mustn't we be firming? mustn't you be firming? mustn't they be firming?
Perfect	V-ing perfect
mustn't I have firmed? mustn't you have firmed? mustn't he have firmed? mustn't we have firmed? mustn't you have firmed? mustn't they have firmed?	mustn't I have been firming? mustn't you have been firming? mustn't he have been firming? mustn't we have been firming? mustn't you have been firming? mustn't they have been firming?