I could place you could place she could place we could place you could place they could place
V-ing form
I could be placing you could be placing she could be placing we could be placing you could be placing they could be placing
Perfect
I could have placed you could have placed she could have placed we could have placed you could have placed they could have placed
V-ing perfect
I could have been placing you could have been placing she could have been placing we could have been placing you could have been placing they could have been placing
Negation
Simple form
I could not place you could not place she could not place we could not place you could not place they could not place
V-ing form
I could not be placing you could not be placing she could not be placing we could not be placing you could not be placing they could not be placing
Perfect
I could not have placed you could not have placed she could not have placed we could not have placed you could not have placed they could not have placed
V-ing perfect
I could not have been placing you could not have been placing she could not have been placing we could not have been placing you could not have been placing they could not have been placing
Interrogative form
Simple form
could I place? could you place? could she place? could we place? could you place? could they place?
V-ing form
could I be placing? could you be placing? could she be placing? could we be placing? could you be placing? could they be placing?
Perfect
could I have placed? could you have placed? could she have placed? could we have placed? could you have placed? could they have placed?
V-ing perfect
could I have been placing? could you have been placing? could she have been placing? could we have been placing? could you have been placing? could they have been placing?
Interro-negative form
Simple form
could I not place? could you not place? could she not place? could we not place? could you not place? could they not place?
V-ing form
could I not be placing? could you not be placing? could she not be placing? could we not be placing? could you not be placing? could they not be placing?
Perfect
could I not have placed? could you not have placed? could she not have placed? could we not have placed? could you not have placed? could they not have placed?
V-ing perfect
could I not have been placing? could you not have been placing? could she not have been placing? could we not have been placing? could you not have been placing? could they not have been placing?