I must joke you must joke he must joke we must joke you must joke they must joke
V-ing form
I must be joking you must be joking he must be joking we must be joking you must be joking they must be joking
Perfect
I must have joked you must have joked he must have joked we must have joked you must have joked they must have joked
V-ing perfect
I must have been joking you must have been joking he must have been joking we must have been joking you must have been joking they must have been joking
Negation
Simple form
I must not joke you must not joke he must not joke we must not joke you must not joke they must not joke
V-ing form
I must not be joking you must not be joking he must not be joking we must not be joking you must not be joking they must not be joking
Perfect
I must not have joked you must not have joked he must not have joked we must not have joked you must not have joked they must not have joked
V-ing perfect
I must not have been joking you must not have been joking he must not have been joking we must not have been joking you must not have been joking they must not have been joking
Interrogative form
Simple form
must I joke? must you joke? must he joke? must we joke? must you joke? must they joke?
V-ing form
must I be joking? must you be joking? must he be joking? must we be joking? must you be joking? must they be joking?
Perfect
must I have joked? must you have joked? must he have joked? must we have joked? must you have joked? must they have joked?
V-ing perfect
must I have been joking? must you have been joking? must he have been joking? must we have been joking? must you have been joking? must they have been joking?
Interro-negative form
Simple form
must I not joke? must you not joke? must he not joke? must we not joke? must you not joke? must they not joke?
V-ing form
must I not be joking? must you not be joking? must he not be joking? must we not be joking? must you not be joking? must they not be joking?
Perfect
must I not have joked? must you not have joked? must he not have joked? must we not have joked? must you not have joked? must they not have joked?
V-ing perfect
must I not have been joking? must you not have been joking? must he not have been joking? must we not have been joking? must you not have been joking? must they not have been joking?