Personal pronouns change case according to how they are used in a sentence. Pronouns functioning as subjects (or subject complements) are in the subjective case; those functioning as objects are in the objective case; and those functioning as possessives are in the possessive case.
Pronoun case
Exercise: Pronoun case (such as I vs. me) 1
Exercise: Pronoun case (such as I vs. me) 2
Exercise: Pronoun case (such as I vs. me) 3
Exercise: Pronoun case: review 1
Exercise: Pronoun case: review 2
personal pronoun I, me, you, she, her, he, him, it, we, us, they, them
case Grammatically, an indicator of the role a noun or pronoun plays in relation to other words: subjective (for subjects and subject complements), objective (for objects), and possessive (for ownership).