must background
Regular verb: background - backgrounded- backgrounded

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must background
you must background
she must background
we must background
you must background
they must background 	I must be backgrounding
you must be backgrounding
she must be backgrounding
we must be backgrounding
you must be backgrounding
they must be backgrounding	I must have backgrounded
you must have backgrounded
she must have backgrounded
we must have backgrounded
you must have backgrounded
they must have backgrounded	I must have been backgrounding
you must have been backgrounding
she must have been backgrounding
we must have been backgrounding
you must have been backgrounding
they must have been backgrounding	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I mustn't background
you mustn't background
she mustn't background
we mustn't background
you mustn't background
they mustn't background 	I mustn't be backgrounding
you mustn't be backgrounding
she mustn't be backgrounding
we mustn't be backgrounding
you mustn't be backgrounding
they mustn't be backgrounding	I mustn't have backgrounded
you mustn't have backgrounded
she mustn't have backgrounded
we mustn't have backgrounded
you mustn't have backgrounded
they mustn't have backgrounded	I mustn't have been backgrounding
you mustn't have been backgrounding
she mustn't have been backgrounding
we mustn't have been backgrounding
you mustn't have been backgrounding
they mustn't have been backgrounding	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I background?
must you background?
must she background?
must we background?
must you background?
must they background? 	must I be backgrounding?
must you be backgrounding?
must she be backgrounding?
must we be backgrounding?
must you be backgrounding?
must they be backgrounding? 	must I have backgrounded?
must you have backgrounded?
must she have backgrounded?
must we have backgrounded?
must you have backgrounded?
must they have backgrounded? 	must I have been backgrounding?
must you have been backgrounding?
must she have been backgrounding?
must we have been backgrounding?
must you have been backgrounding?
must they have been backgrounding? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
mustn't I background?
mustn't you background?
mustn't she background?
mustn't we background?
mustn't you background?
mustn't they background? 	mustn't I be backgrounding?
mustn't you be backgrounding?
mustn't she be backgrounding?
mustn't we be backgrounding?
mustn't you be backgrounding?
mustn't they be backgrounding? 	mustn't I have backgrounded?
mustn't you have backgrounded?
mustn't she have backgrounded?
mustn't we have backgrounded?
mustn't you have backgrounded?
mustn't they have backgrounded? 	mustn't I have been backgrounding?
mustn't you have been backgrounding?
mustn't she have been backgrounding?
mustn't we have been backgrounding?
mustn't you have been backgrounding?
mustn't they have been backgrounding?