English verb conjugation
MUST CONCERN

Regular verb: concern - concerned - concerned

Affirmation

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