I could unhook you could unhook she could unhook we could unhook you could unhook they could unhook
V-ing form
I could be unhooking you could be unhooking she could be unhooking we could be unhooking you could be unhooking they could be unhooking
Perfect
I could have unhooked you could have unhooked she 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 she 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 she 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 she 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 she 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 she 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 she unhook? could we unhook? could you unhook? could they unhook?
V-ing form
could I be unhooking? could you be unhooking? could she be unhooking? could we be unhooking? could you be unhooking? could they be unhooking?
Perfect
could I have unhooked? could you have unhooked? could she 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 she 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 she 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 she 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 she 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 she have been unhooking? couldn't we have been unhooking? couldn't you have been unhooking? couldn't they have been unhooking?