could decaffeinate
Regular verb: decaffeinate - decaffeinated- decaffeinated

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could decaffeinate
you could decaffeinate
he could decaffeinate
we could decaffeinate
you could decaffeinate
they could decaffeinate 	I could be decaffeinating
you could be decaffeinating
he could be decaffeinating
we could be decaffeinating
you could be decaffeinating
they could be decaffeinating	I could have decaffeinated
you could have decaffeinated
he could have decaffeinated
we could have decaffeinated
you could have decaffeinated
they could have decaffeinated	I could have been decaffeinating
you could have been decaffeinating
he could have been decaffeinating
we could have been decaffeinating
you could have been decaffeinating
they could have been decaffeinating	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't decaffeinate
you couldn't decaffeinate
he couldn't decaffeinate
we couldn't decaffeinate
you couldn't decaffeinate
they couldn't decaffeinate 	I couldn't be decaffeinating
you couldn't be decaffeinating
he couldn't be decaffeinating
we couldn't be decaffeinating
you couldn't be decaffeinating
they couldn't be decaffeinating	I couldn't have decaffeinated
you couldn't have decaffeinated
he couldn't have decaffeinated
we couldn't have decaffeinated
you couldn't have decaffeinated
they couldn't have decaffeinated	I couldn't have been decaffeinating
you couldn't have been decaffeinating
he couldn't have been decaffeinating
we couldn't have been decaffeinating
you couldn't have been decaffeinating
they couldn't have been decaffeinating	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I decaffeinate?
could you decaffeinate?
could he decaffeinate?
could we decaffeinate?
could you decaffeinate?
could they decaffeinate? 	could I be decaffeinating?
could you be decaffeinating?
could he be decaffeinating?
could we be decaffeinating?
could you be decaffeinating?
could they be decaffeinating? 	could I have decaffeinated?
could you have decaffeinated?
could he have decaffeinated?
could we have decaffeinated?
could you have decaffeinated?
could they have decaffeinated? 	could I have been decaffeinating?
could you have been decaffeinating?
could he have been decaffeinating?
could we have been decaffeinating?
could you have been decaffeinating?
could they have been decaffeinating? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I decaffeinate?
couldn't you decaffeinate?
couldn't he decaffeinate?
couldn't we decaffeinate?
couldn't you decaffeinate?
couldn't they decaffeinate? 	couldn't I be decaffeinating?
couldn't you be decaffeinating?
couldn't he be decaffeinating?
couldn't we be decaffeinating?
couldn't you be decaffeinating?
couldn't they be decaffeinating? 	couldn't I have decaffeinated?
couldn't you have decaffeinated?
couldn't he have decaffeinated?
couldn't we have decaffeinated?
couldn't you have decaffeinated?
couldn't they have decaffeinated? 	couldn't I have been decaffeinating?
couldn't you have been decaffeinating?
couldn't he have been decaffeinating?
couldn't we have been decaffeinating?
couldn't you have been decaffeinating?
couldn't they have been decaffeinating?