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