If the appositive phrase is needed to define the meaning of a noun then <u>don't use a comma</u>, if the appositive phrase defines enough where it can stand by it's self alone then <u>use commas around it.</u>
Passive voice: a form or set of forms of a verb in which the subject undergoes the action of the verb (e.g. they were killed as opposed to the active form he killed them ).
