English verb conjugation
MUST UNTACK

Regular verb: untack - untacked - untacked

Affirmation

Simple form	V-ing form
I must untack you must untack he must untack we must untack you must untack they must untack	I must be untacking you must be untacking he must be untacking we must be untacking you must be untacking they must be untacking
Perfect	V-ing perfect
I must have untacked you must have untacked he must have untacked we must have untacked you must have untacked they must have untacked	I must have been untacking you must have been untacking he must have been untacking we must have been untacking you must have been untacking they must have been untacking

Negation

Simple form	V-ing form
I mustn't untack you mustn't untack he mustn't untack we mustn't untack you mustn't untack they mustn't untack	I mustn't be untacking you mustn't be untacking he mustn't be untacking we mustn't be untacking you mustn't be untacking they mustn't be untacking
Perfect	V-ing perfect
I mustn't have untacked you mustn't have untacked he mustn't have untacked we mustn't have untacked you mustn't have untacked they mustn't have untacked	I mustn't have been untacking you mustn't have been untacking he mustn't have been untacking we mustn't have been untacking you mustn't have been untacking they mustn't have been untacking

Interrogative form

Simple form	V-ing form
must I untack? must you untack? must he untack? must we untack? must you untack? must they untack?	must I be untacking? must you be untacking? must he be untacking? must we be untacking? must you be untacking? must they be untacking?
Perfect	V-ing perfect
must I have untacked? must you have untacked? must he have untacked? must we have untacked? must you have untacked? must they have untacked?	must I have been untacking? must you have been untacking? must he have been untacking? must we have been untacking? must you have been untacking? must they have been untacking?

Interro-negative form

Simple form	V-ing form
mustn't I untack? mustn't you untack? mustn't he untack? mustn't we untack? mustn't you untack? mustn't they untack?	mustn't I be untacking? mustn't you be untacking? mustn't he be untacking? mustn't we be untacking? mustn't you be untacking? mustn't they be untacking?
Perfect	V-ing perfect
mustn't I have untacked? mustn't you have untacked? mustn't he have untacked? mustn't we have untacked? mustn't you have untacked? mustn't they have untacked?	mustn't I have been untacking? mustn't you have been untacking? mustn't he have been untacking? mustn't we have been untacking? mustn't you have been untacking? mustn't they have been untacking?