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 must not shack you must not shack he must not shack we must not shack you must not shack they must not shack
V-ing form
I must not be shacking you must not be shacking he must not be shacking we must not be shacking you must not be shacking they must not be shacking
Perfect
I must not have shacked you must not have shacked he must not have shacked we must not have shacked you must not have shacked they must not have shacked
V-ing perfect
I must not have been shacking you must not have been shacking he must not have been shacking we must not have been shacking you must not have been shacking they must not 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
must I not shack? must you not shack? must he not shack? must we not shack? must you not shack? must they not shack?
V-ing form
must I not be shacking? must you not be shacking? must he not be shacking? must we not be shacking? must you not be shacking? must they not be shacking?
Perfect
must I not have shacked? must you not have shacked? must he not have shacked? must we not have shacked? must you not have shacked? must they not have shacked?
V-ing perfect
must I not have been shacking? must you not have been shacking? must he not have been shacking? must we not have been shacking? must you not have been shacking? must they not have been shacking?