The easiest and most reliable trick to decide whether to use "who" or "whom" is to substitute the word with a subject or object pronoun:
- If you can replace it with he or she (subject pronouns), use who.
- If you can replace it with him or her (object pronouns), use whom.
This works because who is used as the subject of a sentence or clause (the one performing the action), while whom is used as the object of a verb or preposition (the one receiving the action). Examples:
- "Who went to the store?" → "He went to the store." (he = subject pronoun, so use who)
- "With whom are you going?" → "I am going with him." (him = object pronoun, so use whom)
This trick also helps in questions and relative clauses. For instance, in "Whom did you see?" you can say "I saw him," so "whom" is correct. Additional notes:
- In modern spoken English, especially American English, "who" often replaces "whom" even when "whom" would be grammatically correct, and this is widely accepted in informal contexts.
- "Whom" is still preferred in formal writing, especially after prepositions (e.g., "to whom it may concern").
- The "he/him" test may fail in some tricky sentences like "Who are you?" where the logic seems to suggest "whom," but "who" is correct because it is a subject complement, not an object.
In summary, use the he/him substitution trick as a quick test: if "he/she" fits, use who ; if "him/her" fits, use whom
