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