could oyster
Regular verb: oyster - oystered- oystered

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could oyster
you could oyster
he could oyster
we could oyster
you could oyster
they could oyster 	I could be oystering
you could be oystering
he could be oystering
we could be oystering
you could be oystering
they could be oystering	I could have oystered
you could have oystered
he could have oystered
we could have oystered
you could have oystered
they could have oystered	I could have been oystering
you could have been oystering
he could have been oystering
we could have been oystering
you could have been oystering
they could have been oystering	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could not oyster
you could not oyster
he could not oyster
we could not oyster
you could not oyster
they could not oyster 	I could not be oystering
you could not be oystering
he could not be oystering
we could not be oystering
you could not be oystering
they could not be oystering	I could not have oystered
you could not have oystered
he could not have oystered
we could not have oystered
you could not have oystered
they could not have oystered	I could not have been oystering
you could not have been oystering
he could not have been oystering
we could not have been oystering
you could not have been oystering
they could not have been oystering	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I oyster?
could you oyster?
could he oyster?
could we oyster?
could you oyster?
could they oyster? 	could I be oystering?
could you be oystering?
could he be oystering?
could we be oystering?
could you be oystering?
could they be oystering? 	could I have oystered?
could you have oystered?
could he have oystered?
could we have oystered?
could you have oystered?
could they have oystered? 	could I have been oystering?
could you have been oystering?
could he have been oystering?
could we have been oystering?
could you have been oystering?
could they have been oystering? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I not oyster?
could you not oyster?
could he not oyster?
could we not oyster?
could you not oyster?
could they not oyster? 	could I not be oystering?
could you not be oystering?
could he not be oystering?
could we not be oystering?
could you not be oystering?
could they not be oystering? 	could I not have oystered?
could you not have oystered?
could he not have oystered?
could we not have oystered?
could you not have oystered?
could they not have oystered? 	could I not have been oystering?
could you not have been oystering?
could he not have been oystering?
could we not have been oystering?
could you not have been oystering?
could they not have been oystering?