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 cannot firm you cannot firm he cannot firm we cannot firm you cannot firm they cannot firm	I cannot be firming you cannot be firming he cannot be firming we cannot be firming you cannot be firming they cannot be firming
Perfect	V-ing perfect
I cannot have firmed you cannot have firmed he cannot have firmed we cannot have firmed you cannot have firmed they cannot have firmed	I cannot have been firming you cannot have been firming he cannot have been firming we cannot have been firming you cannot have been firming they cannot 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 I not firm? can you not firm? can he not firm? can we not firm? can you not firm? can they not firm?	can I not be firming? can you not be firming? can he not be firming? can we not be firming? can you not be firming? can they not be firming?
Perfect	V-ing perfect
can I not have firmed? can you not have firmed? can he not have firmed? can we not have firmed? can you not have firmed? can they not have firmed?	can I not have been firming? can you not have been firming? can he not have been firming? can we not have been firming? can you not have been firming? can they not have been firming?