RULE: Choose who or whom depending upon the function of the pronoun in the sentence.
Who is subjective case like the pronouns he, she, they, I, and we.
Use who as the subject or subjective complement of a sentence.
Helpful tip: To see whether who is the correct choice, substitute he for who.
If the sentence sounds correct, then who is the
Whom is objective case like the pronouns him, her, them, me, and us.
Use whom as the direct object, indirect object, or object of a preposition in a sentence.
Helpful tip: To see whether whom is the correct choice, substitute him for whom.
If the sentence sounds correct, then whom is the correct choice.
NOTE: In an adjectival subordinate clause, choose who or whom by determining the
pronoun's function within the subordinate clause.
Link to exercise on who / whom.