must unstring
Irregular verb: unstring - unstrung- unstrung

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must unstring
you must unstring
she must unstring
we must unstring
you must unstring
they must unstring 	I must be unstringing
you must be unstringing
she must be unstringing
we must be unstringing
you must be unstringing
they must be unstringing	I must have unstrung
you must have unstrung
she must have unstrung
we must have unstrung
you must have unstrung
they must have unstrung	I must have been unstringing
you must have been unstringing
she must have been unstringing
we must have been unstringing
you must have been unstringing
they must have been unstringing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I mustn't unstring
you mustn't unstring
she mustn't unstring
we mustn't unstring
you mustn't unstring
they mustn't unstring 	I mustn't be unstringing
you mustn't be unstringing
she mustn't be unstringing
we mustn't be unstringing
you mustn't be unstringing
they mustn't be unstringing	I mustn't have unstrung
you mustn't have unstrung
she mustn't have unstrung
we mustn't have unstrung
you mustn't have unstrung
they mustn't have unstrung	I mustn't have been unstringing
you mustn't have been unstringing
she mustn't have been unstringing
we mustn't have been unstringing
you mustn't have been unstringing
they mustn't have been unstringing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I unstring?
must you unstring?
must she unstring?
must we unstring?
must you unstring?
must they unstring? 	must I be unstringing?
must you be unstringing?
must she be unstringing?
must we be unstringing?
must you be unstringing?
must they be unstringing? 	must I have unstrung?
must you have unstrung?
must she have unstrung?
must we have unstrung?
must you have unstrung?
must they have unstrung? 	must I have been unstringing?
must you have been unstringing?
must she have been unstringing?
must we have been unstringing?
must you have been unstringing?
must they have been unstringing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
mustn't I unstring?
mustn't you unstring?
mustn't she unstring?
mustn't we unstring?
mustn't you unstring?
mustn't they unstring? 	mustn't I be unstringing?
mustn't you be unstringing?
mustn't she be unstringing?
mustn't we be unstringing?
mustn't you be unstringing?
mustn't they be unstringing? 	mustn't I have unstrung?
mustn't you have unstrung?
mustn't she have unstrung?
mustn't we have unstrung?
mustn't you have unstrung?
mustn't they have unstrung? 	mustn't I have been unstringing?
mustn't you have been unstringing?
mustn't she have been unstringing?
mustn't we have been unstringing?
mustn't you have been unstringing?
mustn't they have been unstringing?