I could fire you could fire she could fire we could fire you could fire they could fire
V-ing form
I could be firing you could be firing she could be firing we could be firing you could be firing they could be firing
Perfect
I could have fired you could have fired she 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 she 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 she 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 she 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 she 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 she 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 she fire? could we fire? could you fire? could they fire?
V-ing form
could I be firing? could you be firing? could she be firing? could we be firing? could you be firing? could they be firing?
Perfect
could I have fired? could you have fired? could she 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 she 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 she 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 she 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 she 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 she have been firing? couldn't we have been firing? couldn't you have been firing? couldn't they have been firing?