must trouble
Regular verb: trouble - troubled- troubled

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must trouble
you must trouble
she must trouble
we must trouble
you must trouble
they must trouble 	I must be troubling
you must be troubling
she must be troubling
we must be troubling
you must be troubling
they must be troubling	I must have troubled
you must have troubled
she must have troubled
we must have troubled
you must have troubled
they must have troubled	I must have been troubling
you must have been troubling
she must have been troubling
we must have been troubling
you must have been troubling
they must have been troubling	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I mustn't trouble
you mustn't trouble
she mustn't trouble
we mustn't trouble
you mustn't trouble
they mustn't trouble 	I mustn't be troubling
you mustn't be troubling
she mustn't be troubling
we mustn't be troubling
you mustn't be troubling
they mustn't be troubling	I mustn't have troubled
you mustn't have troubled
she mustn't have troubled
we mustn't have troubled
you mustn't have troubled
they mustn't have troubled	I mustn't have been troubling
you mustn't have been troubling
she mustn't have been troubling
we mustn't have been troubling
you mustn't have been troubling
they mustn't have been troubling	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I trouble?
must you trouble?
must she trouble?
must we trouble?
must you trouble?
must they trouble? 	must I be troubling?
must you be troubling?
must she be troubling?
must we be troubling?
must you be troubling?
must they be troubling? 	must I have troubled?
must you have troubled?
must she have troubled?
must we have troubled?
must you have troubled?
must they have troubled? 	must I have been troubling?
must you have been troubling?
must she have been troubling?
must we have been troubling?
must you have been troubling?
must they have been troubling? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
mustn't I trouble?
mustn't you trouble?
mustn't she trouble?
mustn't we trouble?
mustn't you trouble?
mustn't they trouble? 	mustn't I be troubling?
mustn't you be troubling?
mustn't she be troubling?
mustn't we be troubling?
mustn't you be troubling?
mustn't they be troubling? 	mustn't I have troubled?
mustn't you have troubled?
mustn't she have troubled?
mustn't we have troubled?
mustn't you have troubled?
mustn't they have troubled? 	mustn't I have been troubling?
mustn't you have been troubling?
mustn't she have been troubling?
mustn't we have been troubling?
mustn't you have been troubling?
mustn't they have been troubling?