could butter
Regular verb: butter - buttered- buttered

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could butter
you could butter
he could butter
we could butter
you could butter
they could butter 	I could be buttering
you could be buttering
he could be buttering
we could be buttering
you could be buttering
they could be buttering	I could have buttered
you could have buttered
he could have buttered
we could have buttered
you could have buttered
they could have buttered	I could have been buttering
you could have been buttering
he could have been buttering
we could have been buttering
you could have been buttering
they could have been buttering	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could not butter
you could not butter
he could not butter
we could not butter
you could not butter
they could not butter 	I could not be buttering
you could not be buttering
he could not be buttering
we could not be buttering
you could not be buttering
they could not be buttering	I could not have buttered
you could not have buttered
he could not have buttered
we could not have buttered
you could not have buttered
they could not have buttered	I could not have been buttering
you could not have been buttering
he could not have been buttering
we could not have been buttering
you could not have been buttering
they could not have been buttering	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I butter?
could you butter?
could he butter?
could we butter?
could you butter?
could they butter? 	could I be buttering?
could you be buttering?
could he be buttering?
could we be buttering?
could you be buttering?
could they be buttering? 	could I have buttered?
could you have buttered?
could he have buttered?
could we have buttered?
could you have buttered?
could they have buttered? 	could I have been buttering?
could you have been buttering?
could he have been buttering?
could we have been buttering?
could you have been buttering?
could they have been buttering? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I not butter?
could you not butter?
could he not butter?
could we not butter?
could you not butter?
could they not butter? 	could I not be buttering?
could you not be buttering?
could he not be buttering?
could we not be buttering?
could you not be buttering?
could they not be buttering? 	could I not have buttered?
could you not have buttered?
could he not have buttered?
could we not have buttered?
could you not have buttered?
could they not have buttered? 	could I not have been buttering?
could you not have been buttering?
could he not have been buttering?
could we not have been buttering?
could you not have been buttering?
could they not have been buttering?