must trouble
Regular verb: trouble - troubled- troubled

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must trouble
you must trouble
he must trouble
we must trouble
you must trouble
they must trouble 	I must be troubling
you must be troubling
he must be troubling
we must be troubling
you must be troubling
they must be troubling	I must have troubled
you must have troubled
he 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
he 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 must not trouble
you must not trouble
he must not trouble
we must not trouble
you must not trouble
they must not trouble 	I must not be troubling
you must not be troubling
he must not be troubling
we must not be troubling
you must not be troubling
they must not be troubling	I must not have troubled
you must not have troubled
he must not have troubled
we must not have troubled
you must not have troubled
they must not have troubled	I must not have been troubling
you must not have been troubling
he must not have been troubling
we must not have been troubling
you must not have been troubling
they must not have been troubling	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I trouble?
must you trouble?
must he trouble?
must we trouble?
must you trouble?
must they trouble? 	must I be troubling?
must you be troubling?
must he be troubling?
must we be troubling?
must you be troubling?
must they be troubling? 	must I have troubled?
must you have troubled?
must he 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 he 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 	
must I not trouble?
must you not trouble?
must he not trouble?
must we not trouble?
must you not trouble?
must they not trouble? 	must I not be troubling?
must you not be troubling?
must he not be troubling?
must we not be troubling?
must you not be troubling?
must they not be troubling? 	must I not have troubled?
must you not have troubled?
must he not have troubled?
must we not have troubled?
must you not have troubled?
must they not have troubled? 	must I not have been troubling?
must you not have been troubling?
must he not have been troubling?
must we not have been troubling?
must you not have been troubling?
must they not have been troubling?