English verb conjugation
COULD TURN

Regular verb: turn - turned - turned

Affirmation

Simple form	V-ing form
I could turn you could turn he could turn we could turn you could turn they could turn	I could be turning you could be turning he 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 he 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 he 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 couldn't turn you couldn't turn he couldn't turn we couldn't turn you couldn't turn they couldn't turn	I couldn't be turning you couldn't be turning he couldn't be turning we couldn't be turning you couldn't be turning they couldn't be turning
Perfect	V-ing perfect
I couldn't have turned you couldn't have turned he couldn't have turned we couldn't have turned you couldn't have turned they couldn't have turned	I couldn't have been turning you couldn't have been turning he couldn't have been turning we couldn't have been turning you couldn't have been turning they couldn't have been turning

Interrogative form

Simple form	V-ing form
could I turn? could you turn? could he turn? could we turn? could you turn? could they turn?	could I be turning? could you be turning? could he 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 he 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 he 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
couldn't I turn? couldn't you turn? couldn't he turn? couldn't we turn? couldn't you turn? couldn't they turn?	couldn't I be turning? couldn't you be turning? couldn't he be turning? couldn't we be turning? couldn't you be turning? couldn't they be turning?
Perfect	V-ing perfect
couldn't I have turned? couldn't you have turned? couldn't he have turned? couldn't we have turned? couldn't you have turned? couldn't they have turned?	couldn't I have been turning? couldn't you have been turning? couldn't he have been turning? couldn't we have been turning? couldn't you have been turning? couldn't they have been turning?