I must improvise you must improvise he must improvise we must improvise you must improvise they must improvise
V-ing form
I must be improvising you must be improvising he must be improvising we must be improvising you must be improvising they must be improvising
Perfect
I must have improvised you must have improvised he must have improvised we must have improvised you must have improvised they must have improvised
V-ing perfect
I must have been improvising you must have been improvising he must have been improvising we must have been improvising you must have been improvising they must have been improvising
Negation
Simple form
I mustn't improvise you mustn't improvise he mustn't improvise we mustn't improvise you mustn't improvise they mustn't improvise
V-ing form
I mustn't be improvising you mustn't be improvising he mustn't be improvising we mustn't be improvising you mustn't be improvising they mustn't be improvising
Perfect
I mustn't have improvised you mustn't have improvised he mustn't have improvised we mustn't have improvised you mustn't have improvised they mustn't have improvised
V-ing perfect
I mustn't have been improvising you mustn't have been improvising he mustn't have been improvising we mustn't have been improvising you mustn't have been improvising they mustn't have been improvising
Interrogative form
Simple form
must I improvise? must you improvise? must he improvise? must we improvise? must you improvise? must they improvise?
V-ing form
must I be improvising? must you be improvising? must he be improvising? must we be improvising? must you be improvising? must they be improvising?
Perfect
must I have improvised? must you have improvised? must he have improvised? must we have improvised? must you have improvised? must they have improvised?
V-ing perfect
must I have been improvising? must you have been improvising? must he have been improvising? must we have been improvising? must you have been improvising? must they have been improvising?
Interro-negative form
Simple form
mustn't I improvise? mustn't you improvise? mustn't he improvise? mustn't we improvise? mustn't you improvise? mustn't they improvise?
V-ing form
mustn't I be improvising? mustn't you be improvising? mustn't he be improvising? mustn't we be improvising? mustn't you be improvising? mustn't they be improvising?
Perfect
mustn't I have improvised? mustn't you have improvised? mustn't he have improvised? mustn't we have improvised? mustn't you have improvised? mustn't they have improvised?
V-ing perfect
mustn't I have been improvising? mustn't you have been improvising? mustn't he have been improvising? mustn't we have been improvising? mustn't you have been improvising? mustn't they have been improvising?