We're always getting this wrong on TSR! Also had a friend ask me to explain it so figured I'd make a thread in case it's helpful to others too According to
Oxford English Dictionaries:
"who should be used in the subject position in a sentence, while whom should be used in the object position, and also after a preposition", but a handy basic/less abstract way to think of it is this:
You take a phrase (1), imagine using either
he/she or
him/her (whichever makes grammatical sense) in an alternative phrase that is otherwise effectively the same, instead of
who or
whom (2), and then determine which to use accordingly (colour code indicates which to use) (3) e.g.
Example A:
1)
Your phrase:My friend Hannah, wh.. has finally met the man of her dreams2)
Imagine:My friend Hannah,
she finally met the man of her dreams*
3)
Determination:The correct word to use is therefore
whoExample B:
1)
Your phrase:My friend Hannah, for wh.. finally meeting the man of her dreams was wonderful2)
Imagine:My friend Hannah, for
her finally meeting the man of her dreams was wonderful*
3)
Determination:The correct word to use is therefore
whom