could firm
Regular verb: firm - firmed- firmed

Affirmation 	
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I could firm
you could firm
she could firm
we could firm
you could firm
they could firm 	I could be firming
you could be firming
she could be firming
we could be firming
you could be firming
they could be firming	I could have firmed
you could have firmed
she 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
she could have been firming
we could have been firming
you could have been firming
they could have been firming	

Negation 	
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I could not firm
you could not firm
she could not firm
we could not firm
you could not firm
they could not firm 	I could not be firming
you could not be firming
she could not be firming
we could not be firming
you could not be firming
they could not be firming	I could not have firmed
you could not have firmed
she could not have firmed
we could not have firmed
you could not have firmed
they could not have firmed	I could not have been firming
you could not have been firming
she could not have been firming
we could not have been firming
you could not have been firming
they could not have been firming	

Interrogative form 	
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could I firm?
could you firm?
could she firm?
could we firm?
could you firm?
could they firm? 	could I be firming?
could you be firming?
could she be firming?
could we be firming?
could you be firming?
could they be firming? 	could I have firmed?
could you have firmed?
could she 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 she have been firming?
could we have been firming?
could you have been firming?
could they have been firming? 	

Interro-negative form 	
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could I not firm?
could you not firm?
could she not firm?
could we not firm?
could you not firm?
could they not firm? 	could I not be firming?
could you not be firming?
could she not be firming?
could we not be firming?
could you not be firming?
could they not be firming? 	could I not have firmed?
could you not have firmed?
could she not have firmed?
could we not have firmed?
could you not have firmed?
could they not have firmed? 	could I not have been firming?
could you not have been firming?
could she not have been firming?
could we not have been firming?
could you not have been firming?
could they not have been firming?