English verb conjugation
COULD TURN

Regular verb: turn - turned - turned

Affirmation

Simple form	V-ing form
I could turn you could turn she could turn we could turn you could turn they could turn	I could be turning you could be turning she could be turning we could be turning you could be turning they could be turning
Perfect	V-ing perfect
I could have turned you could have turned she could have turned we could have turned you could have turned they could have turned	I could have been turning you could have been turning she could have been turning we could have been turning you could have been turning they could have been turning

Negation

Simple form	V-ing form
I could not turn you could not turn she could not turn we could not turn you could not turn they could not turn	I could not be turning you could not be turning she could not be turning we could not be turning you could not be turning they could not be turning
Perfect	V-ing perfect
I could not have turned you could not have turned she could not have turned we could not have turned you could not have turned they could not have turned	I could not have been turning you could not have been turning she could not have been turning we could not have been turning you could not have been turning they could not have been turning

Interrogative form

Simple form	V-ing form
could I turn? could you turn? could she turn? could we turn? could you turn? could they turn?	could I be turning? could you be turning? could she be turning? could we be turning? could you be turning? could they be turning?
Perfect	V-ing perfect
could I have turned? could you have turned? could she have turned? could we have turned? could you have turned? could they have turned?	could I have been turning? could you have been turning? could she have been turning? could we have been turning? could you have been turning? could they have been turning?

Interro-negative form

Simple form	V-ing form
could I not turn? could you not turn? could she not turn? could we not turn? could you not turn? could they not turn?	could I not be turning? could you not be turning? could she not be turning? could we not be turning? could you not be turning? could they not be turning?
Perfect	V-ing perfect
could I not have turned? could you not have turned? could she not have turned? could we not have turned? could you not have turned? could they not have turned?	could I not have been turning? could you not have been turning? could she not have been turning? could we not have been turning? could you not have been turning? could they not have been turning?