English verb conjugation
COULD FIRM

Regular verb: firm - firmed - firmed

Affirmation

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

Negation

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

Interrogative form

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

Interro-negative form

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