Caroline receives e-mail from friends who she knows well, from acquaintances who's names are only vaguely familiar, and from strangers about who she knows nothing at all.
Chris's correction:
object pronoun-whom
subject pronoun-who (not whom)
possessive pronoun-whose
pronouns
antecedents
Answer:
Caroline receives e-mail from friends whom she knows well, from acquaintances whose names are only vaguely familiar, and from strangers about whom she knows nothing at all.
Doubt:
what is the strategy for deciding on the use of Object or Subject Pronoun?
Great questions. I recommend that you use the context of the sentence to determine whether you should use a subject or object pronoun. Let's break this problem down issue by issue.
Caroline receives e-mail from friends whom she knows well
She knows (who or whom) well? If you're struggling with answering that question swap out who and whom with an easier to read equivalent pronoun such as he and him.
She knows (he or him) well. Here, him clearly works better and that makes sense because him is the object of the verb to know so we'd naturally want to use the object pronoun him and thus we clearly need the object pronoun whom in the original sentence.
and from strangers about whom she knows nothing at all.
When used in conjunction with a preposition such as "about" in this case, we need to use an object pronoun as the pronoun is the object of the preposition.
We only use the subject pronoun "who" when that pronoun is replacing an actor in the sentence. Actors in the sentence can be subjects with a verb pair or a subject that had a verb pair earlier in the sentence.
Thanks,
Chris