must shack
Regular verb: shack - shacked- shacked

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must shack
you must shack
she must shack
we must shack
you must shack
they must shack 	I must be shacking
you must be shacking
she must be shacking
we must be shacking
you must be shacking
they must be shacking	I must have shacked
you must have shacked
she must have shacked
we must have shacked
you must have shacked
they must have shacked	I must have been shacking
you must have been shacking
she must have been shacking
we must have been shacking
you must have been shacking
they must have been shacking	

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

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I not shack?
must you not shack?
must she not shack?
must we not shack?
must you not shack?
must they not shack? 	must I not be shacking?
must you not be shacking?
must she not be shacking?
must we not be shacking?
must you not be shacking?
must they not be shacking? 	must I not have shacked?
must you not have shacked?
must she not have shacked?
must we not have shacked?
must you not have shacked?
must they not have shacked? 	must I not have been shacking?
must you not have been shacking?
must she not have been shacking?
must we not have been shacking?
must you not have been shacking?
must they not have been shacking?