English verb conjugation
COULD RETURN

Regular verb: return - returned - returned

Affirmation

Simple form	V-ing form
I could return you could return he could return we could return you could return they could return	I could be returning you could be returning he could be returning we could be returning you could be returning they could be returning
Perfect	V-ing perfect
I could have returned you could have returned he could have returned we could have returned you could have returned they could have returned	I could have been returning you could have been returning he could have been returning we could have been returning you could have been returning they could have been returning

Negation

Simple form	V-ing form
I could not return you could not return he could not return we could not return you could not return they could not return	I could not be returning you could not be returning he could not be returning we could not be returning you could not be returning they could not be returning
Perfect	V-ing perfect
I could not have returned you could not have returned he could not have returned we could not have returned you could not have returned they could not have returned	I could not have been returning you could not have been returning he could not have been returning we could not have been returning you could not have been returning they could not have been returning

Interrogative form

Simple form	V-ing form
could I return? could you return? could he return? could we return? could you return? could they return?	could I be returning? could you be returning? could he be returning? could we be returning? could you be returning? could they be returning?
Perfect	V-ing perfect
could I have returned? could you have returned? could he have returned? could we have returned? could you have returned? could they have returned?	could I have been returning? could you have been returning? could he have been returning? could we have been returning? could you have been returning? could they have been returning?

Interro-negative form

Simple form	V-ing form
could I not return? could you not return? could he not return? could we not return? could you not return? could they not return?	could I not be returning? could you not be returning? could he not be returning? could we not be returning? could you not be returning? could they not be returning?
Perfect	V-ing perfect
could I not have returned? could you not have returned? could he not have returned? could we not have returned? could you not have returned? could they not have returned?	could I not have been returning? could you not have been returning? could he not have been returning? could we not have been returning? could you not have been returning? could they not have been returning?