could blister
Regular verb: blister - blistered- blistered

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could blister
you could blister
he could blister
we could blister
you could blister
they could blister 	I could be blistering
you could be blistering
he could be blistering
we could be blistering
you could be blistering
they could be blistering	I could have blistered
you could have blistered
he could have blistered
we could have blistered
you could have blistered
they could have blistered	I could have been blistering
you could have been blistering
he could have been blistering
we could have been blistering
you could have been blistering
they could have been blistering	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could not blister
you could not blister
he could not blister
we could not blister
you could not blister
they could not blister 	I could not be blistering
you could not be blistering
he could not be blistering
we could not be blistering
you could not be blistering
they could not be blistering	I could not have blistered
you could not have blistered
he could not have blistered
we could not have blistered
you could not have blistered
they could not have blistered	I could not have been blistering
you could not have been blistering
he could not have been blistering
we could not have been blistering
you could not have been blistering
they could not have been blistering	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I blister?
could you blister?
could he blister?
could we blister?
could you blister?
could they blister? 	could I be blistering?
could you be blistering?
could he be blistering?
could we be blistering?
could you be blistering?
could they be blistering? 	could I have blistered?
could you have blistered?
could he have blistered?
could we have blistered?
could you have blistered?
could they have blistered? 	could I have been blistering?
could you have been blistering?
could he have been blistering?
could we have been blistering?
could you have been blistering?
could they have been blistering? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I not blister?
could you not blister?
could he not blister?
could we not blister?
could you not blister?
could they not blister? 	could I not be blistering?
could you not be blistering?
could he not be blistering?
could we not be blistering?
could you not be blistering?
could they not be blistering? 	could I not have blistered?
could you not have blistered?
could he not have blistered?
could we not have blistered?
could you not have blistered?
could they not have blistered? 	could I not have been blistering?
could you not have been blistering?
could he not have been blistering?
could we not have been blistering?
could you not have been blistering?
could they not have been blistering?