must concuss
Regular verb: concuss - concussed- concussed

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must concuss
you must concuss
she must concuss
we must concuss
you must concuss
they must concuss 	I must be concussing
you must be concussing
she must be concussing
we must be concussing
you must be concussing
they must be concussing	I must have concussed
you must have concussed
she must have concussed
we must have concussed
you must have concussed
they must have concussed	I must have been concussing
you must have been concussing
she must have been concussing
we must have been concussing
you must have been concussing
they must have been concussing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I mustn't concuss
you mustn't concuss
she mustn't concuss
we mustn't concuss
you mustn't concuss
they mustn't concuss 	I mustn't be concussing
you mustn't be concussing
she mustn't be concussing
we mustn't be concussing
you mustn't be concussing
they mustn't be concussing	I mustn't have concussed
you mustn't have concussed
she mustn't have concussed
we mustn't have concussed
you mustn't have concussed
they mustn't have concussed	I mustn't have been concussing
you mustn't have been concussing
she mustn't have been concussing
we mustn't have been concussing
you mustn't have been concussing
they mustn't have been concussing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I concuss?
must you concuss?
must she concuss?
must we concuss?
must you concuss?
must they concuss? 	must I be concussing?
must you be concussing?
must she be concussing?
must we be concussing?
must you be concussing?
must they be concussing? 	must I have concussed?
must you have concussed?
must she have concussed?
must we have concussed?
must you have concussed?
must they have concussed? 	must I have been concussing?
must you have been concussing?
must she have been concussing?
must we have been concussing?
must you have been concussing?
must they have been concussing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
mustn't I concuss?
mustn't you concuss?
mustn't she concuss?
mustn't we concuss?
mustn't you concuss?
mustn't they concuss? 	mustn't I be concussing?
mustn't you be concussing?
mustn't she be concussing?
mustn't we be concussing?
mustn't you be concussing?
mustn't they be concussing? 	mustn't I have concussed?
mustn't you have concussed?
mustn't she have concussed?
mustn't we have concussed?
mustn't you have concussed?
mustn't they have concussed? 	mustn't I have been concussing?
mustn't you have been concussing?
mustn't she have been concussing?
mustn't we have been concussing?
mustn't you have been concussing?
mustn't they have been concussing?