I could place you could place he could place we could place you could place they could place
V-ing form
I could be placing you could be placing he could be placing we could be placing you could be placing they could be placing
Perfect
I could have placed you could have placed he 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 he could have been placing we could have been placing you could have been placing they could have been placing
Negation
Simple form
I couldn't place you couldn't place he couldn't place we couldn't place you couldn't place they couldn't place
V-ing form
I couldn't be placing you couldn't be placing he couldn't be placing we couldn't be placing you couldn't be placing they couldn't be placing
Perfect
I couldn't have placed you couldn't have placed he couldn't have placed we couldn't have placed you couldn't have placed they couldn't have placed
V-ing perfect
I couldn't have been placing you couldn't have been placing he couldn't have been placing we couldn't have been placing you couldn't have been placing they couldn't have been placing
Interrogative form
Simple form
could I place? could you place? could he place? could we place? could you place? could they place?
V-ing form
could I be placing? could you be placing? could he be placing? could we be placing? could you be placing? could they be placing?
Perfect
could I have placed? could you have placed? could he 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 he have been placing? could we have been placing? could you have been placing? could they have been placing?
Interro-negative form
Simple form
couldn't I place? couldn't you place? couldn't he place? couldn't we place? couldn't you place? couldn't they place?
V-ing form
couldn't I be placing? couldn't you be placing? couldn't he be placing? couldn't we be placing? couldn't you be placing? couldn't they be placing?
Perfect
couldn't I have placed? couldn't you have placed? couldn't he have placed? couldn't we have placed? couldn't you have placed? couldn't they have placed?
V-ing perfect
couldn't I have been placing? couldn't you have been placing? couldn't he have been placing? couldn't we have been placing? couldn't you have been placing? couldn't they have been placing?