I could refine you could refine he could refine we could refine you could refine they could refine
Forma con V-ing
I could be refining you could be refining he could be refining we could be refining you could be refining they could be refining
Perfecto
I could have refined you could have refined he could have refined we could have refined you could have refined they could have refined
Perfecto con V-ing
I could have been refining you could have been refining he could have been refining we could have been refining you could have been refining they could have been refining
Negación
Forma simple
I couldn't refine you couldn't refine he couldn't refine we couldn't refine you couldn't refine they couldn't refine
Forma con V-ing
I couldn't be refining you couldn't be refining he couldn't be refining we couldn't be refining you couldn't be refining they couldn't be refining
Perfecto
I couldn't have refined you couldn't have refined he couldn't have refined we couldn't have refined you couldn't have refined they couldn't have refined
Perfecto con V-ing
I couldn't have been refining you couldn't have been refining he couldn't have been refining we couldn't have been refining you couldn't have been refining they couldn't have been refining
Forma interrogativa
Forma simple
could I refine? could you refine? could he refine? could we refine? could you refine? could they refine?
Forma con V-ing
could I be refining? could you be refining? could he be refining? could we be refining? could you be refining? could they be refining?
Perfecto
could I have refined? could you have refined? could he have refined? could we have refined? could you have refined? could they have refined?
Perfecto con V-ing
could I have been refining? could you have been refining? could he have been refining? could we have been refining? could you have been refining? could they have been refining?
Forma interro-negativa
Forma simple
couldn't I refine? couldn't you refine? couldn't he refine? couldn't we refine? couldn't you refine? couldn't they refine?
Forma con V-ing
couldn't I be refining? couldn't you be refining? couldn't he be refining? couldn't we be refining? couldn't you be refining? couldn't they be refining?
Perfecto
couldn't I have refined? couldn't you have refined? couldn't he have refined? couldn't we have refined? couldn't you have refined? couldn't they have refined?
Perfecto con V-ing
couldn't I have been refining? couldn't you have been refining? couldn't he have been refining? couldn't we have been refining? couldn't you have been refining? couldn't they have been refining?