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