How do I know when to use who or whom?
Who replaces the subject of a clause or sentence.
Whom replaces the object in a sentence.
How do I decide?
Replace who with he, she, or they.
Replace whom with him, her, or them.
Can you tell me (who, whom) turned in their outlines?
They turned in their outlines. The answer is who.
Do you know for (who, whom) these flowers were sent?
The flowers were sent for them. The answer is whom.
Who or Whom are you voting for?
You are voting for ___.
You are voting for they?
You are voting for them?
The answer, then, is whom.