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