could stain
Regular verb: stain - stained- stained

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could stain
you could stain
he could stain
we could stain
you could stain
they could stain 	I could be staining
you could be staining
he could be staining
we could be staining
you could be staining
they could be staining	I could have stained
you could have stained
he could have stained
we could have stained
you could have stained
they could have stained	I could have been staining
you could have been staining
he could have been staining
we could have been staining
you could have been staining
they could have been staining	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could not stain
you could not stain
he could not stain
we could not stain
you could not stain
they could not stain 	I could not be staining
you could not be staining
he could not be staining
we could not be staining
you could not be staining
they could not be staining	I could not have stained
you could not have stained
he could not have stained
we could not have stained
you could not have stained
they could not have stained	I could not have been staining
you could not have been staining
he could not have been staining
we could not have been staining
you could not have been staining
they could not have been staining	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I stain?
could you stain?
could he stain?
could we stain?
could you stain?
could they stain? 	could I be staining?
could you be staining?
could he be staining?
could we be staining?
could you be staining?
could they be staining? 	could I have stained?
could you have stained?
could he have stained?
could we have stained?
could you have stained?
could they have stained? 	could I have been staining?
could you have been staining?
could he have been staining?
could we have been staining?
could you have been staining?
could they have been staining? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I not stain?
could you not stain?
could he not stain?
could we not stain?
could you not stain?
could they not stain? 	could I not be staining?
could you not be staining?
could he not be staining?
could we not be staining?
could you not be staining?
could they not be staining? 	could I not have stained?
could you not have stained?
could he not have stained?
could we not have stained?
could you not have stained?
could they not have stained? 	could I not have been staining?
could you not have been staining?
could he not have been staining?
could we not have been staining?
could you not have been staining?
could they not have been staining?