Question

How do you know when to use whom and when to use who?

Answer 1

In a sentence, WHO and WHOM have different syntactic functions.

Step-by-step explanation:

WHO

• WHO can be used as the subject of a sentence. For example, "who is your brother?"
• WHO can be replaced by he or she.

WHOM

• WHOM is used as the object of the verb or object of a preposition as in "who is helping whom?" or "I know the person to whom the letter was addressed" respectively.
• WHOM can be replaced by him or her.