must sack
Regular verb: sack - sacked- sacked

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must sack
you must sack
he must sack
we must sack
you must sack
they must sack 	I must be sacking
you must be sacking
he must be sacking
we must be sacking
you must be sacking
they must be sacking	I must have sacked
you must have sacked
he must have sacked
we must have sacked
you must have sacked
they must have sacked	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 	V-ing form 	Perfect 	V-ing perfect 	
I mustn't sack
you mustn't sack
he mustn't sack
we mustn't sack
you mustn't sack
they mustn't sack 	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	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	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 	V-ing form 	Perfect 	V-ing perfect 	
must I sack?
must you sack?
must he sack?
must we sack?
must you sack?
must they sack? 	must I be sacking?
must you be sacking?
must he be sacking?
must we be sacking?
must you be sacking?
must they be sacking? 	must I have sacked?
must you have sacked?
must he have sacked?
must we have sacked?
must you have sacked?
must they have sacked? 	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 	V-ing form 	Perfect 	V-ing perfect 	
mustn't I sack?
mustn't you sack?
mustn't he sack?
mustn't we sack?
mustn't you sack?
mustn't they sack? 	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? 	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? 	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?