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