English verb conjugation
CAN FIRM

Regular verb: firm - firmed - firmed

Affirmation

Simple form	V-ing form
I can firm you can firm she can firm we can firm you can firm they can firm	I can be firming you can be firming she 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 she 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 she 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 she 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 she 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 she 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 she 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 she firm? can we firm? can you firm? can they firm?	can I be firming? can you be firming? can she 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 she 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 she 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 she 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 she 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 she 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 she have been firming? can't we have been firming? can't you have been firming? can't they have been firming?