can firm
Regular verb: firm - firmed- firmed

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
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	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 	Perfect 	V-ing perfect 	
I cannot firm
you cannot firm
she cannot firm
we cannot firm
you cannot firm
they cannot firm 	I cannot be firming
you cannot be firming
she cannot be firming
we cannot be firming
you cannot be firming
they cannot be firming	I cannot have firmed
you cannot have firmed
she 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
she 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 	Perfect 	V-ing perfect 	
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? 	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 	Perfect 	V-ing perfect 	
can I not firm?
can you not firm?
can she 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 she not be firming?
can we not be firming?
can you not be firming?
can they not be firming? 	can I not have firmed?
can you not have firmed?
can she 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 she not have been firming?
can we not have been firming?
can you not have been firming?
can they not have been firming?