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