must concern
Regular verb: concern - concerned- concerned

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must concern
you must concern
she must concern
we must concern
you must concern
they must concern 	I must be concerning
you must be concerning
she must be concerning
we must be concerning
you must be concerning
they must be concerning	I must have concerned
you must have concerned
she must have concerned
we must have concerned
you must have concerned
they must have concerned	I must have been concerning
you must have been concerning
she must have been concerning
we must have been concerning
you must have been concerning
they must have been concerning	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must not concern
you must not concern
she must not concern
we must not concern
you must not concern
they must not concern 	I must not be concerning
you must not be concerning
she must not be concerning
we must not be concerning
you must not be concerning
they must not be concerning	I must not have concerned
you must not have concerned
she must not have concerned
we must not have concerned
you must not have concerned
they must not have concerned	I must not have been concerning
you must not have been concerning
she must not have been concerning
we must not have been concerning
you must not have been concerning
they must not have been concerning	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I concern?
must you concern?
must she concern?
must we concern?
must you concern?
must they concern? 	must I be concerning?
must you be concerning?
must she be concerning?
must we be concerning?
must you be concerning?
must they be concerning? 	must I have concerned?
must you have concerned?
must she have concerned?
must we have concerned?
must you have concerned?
must they have concerned? 	must I have been concerning?
must you have been concerning?
must she have been concerning?
must we have been concerning?
must you have been concerning?
must they have been concerning? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I not concern?
must you not concern?
must she not concern?
must we not concern?
must you not concern?
must they not concern? 	must I not be concerning?
must you not be concerning?
must she not be concerning?
must we not be concerning?
must you not be concerning?
must they not be concerning? 	must I not have concerned?
must you not have concerned?
must she not have concerned?
must we not have concerned?
must you not have concerned?
must they not have concerned? 	must I not have been concerning?
must you not have been concerning?
must she not have been concerning?
must we not have been concerning?
must you not have been concerning?
must they not have been concerning?