English verb conjugation
CAN FIRM

Regular verb: firm - firmed - firmed

Affirmation

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

Negation

Simple form	V-ing form
I can't firm you can't firm he can't firm we can't firm you can't firm they can't firm	I can't be firming you can't be firming he can't be firming we can't be firming you can't be firming they can't be firming
Perfect	V-ing perfect
I can't have firmed you can't have firmed he can't have firmed we can't have firmed you can't have firmed they can't have firmed	I can't have been firming you can't have been firming he can't have been firming we can't have been firming you can't have been firming they can't have been firming

Interrogative form

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

Interro-negative form

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