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 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	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 	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'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? 	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?