I must joke you must joke she must joke we must joke you must joke they must joke
V-ing form
I must be joking you must be joking she must be joking we must be joking you must be joking they must be joking
Perfect
I must have joked you must have joked she 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 she must have been joking we must have been joking you must have been joking they must have been joking
Negation
Simple form
I mustn't joke you mustn't joke she mustn't joke we mustn't joke you mustn't joke they mustn't joke
V-ing form
I mustn't be joking you mustn't be joking she mustn't be joking we mustn't be joking you mustn't be joking they mustn't be joking
Perfect
I mustn't have joked you mustn't have joked she mustn't have joked we mustn't have joked you mustn't have joked they mustn't have joked
V-ing perfect
I mustn't have been joking you mustn't have been joking she mustn't have been joking we mustn't have been joking you mustn't have been joking they mustn't have been joking
Interrogative form
Simple form
must I joke? must you joke? must she joke? must we joke? must you joke? must they joke?
V-ing form
must I be joking? must you be joking? must she be joking? must we be joking? must you be joking? must they be joking?
Perfect
must I have joked? must you have joked? must she 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 she have been joking? must we have been joking? must you have been joking? must they have been joking?
Interro-negative form
Simple form
mustn't I joke? mustn't you joke? mustn't she joke? mustn't we joke? mustn't you joke? mustn't they joke?
V-ing form
mustn't I be joking? mustn't you be joking? mustn't she be joking? mustn't we be joking? mustn't you be joking? mustn't they be joking?
Perfect
mustn't I have joked? mustn't you have joked? mustn't she have joked? mustn't we have joked? mustn't you have joked? mustn't they have joked?
V-ing perfect
mustn't I have been joking? mustn't you have been joking? mustn't she have been joking? mustn't we have been joking? mustn't you have been joking? mustn't they have been joking?