If a question were asked about the sentence, would the answer be “he/she/they,” or “him/her/them”?
This is probably the easiest way to remember the difference between “who” and “whom,” and the majority of the time, this will get you the correct answer. If a question about the action being described would be answered with “he —,” then the correct form is “who.” If a question about the action being described would be answered with “him,” then the correct form is “whom.” Just remember that the words with M’s at the end go together. He = Who, and Him = Whom. Let’s look at a simple sentence addressing this issue:
The Welsh corgi is a small herding dog, and is well-known because of Queen Elizabeth II, who/whom keeps several of them.
It’s likely that in this sentence, your “ear” would tell you to choose “who”—and that would be correct. But if your “ear” fails you, then you can determine the correct answer by asking yourself about the action being described in the relevant part of the sentence: “Who keeps corgis?” And then answer that question with a pronoun: “She does.” Since “she” is appropriate here, we use “who” in the sentence. Make sense? Let’s try it on another sentence.
If the computer system continues to cause problems over the weekend, the secretary is supposed to call whoever/whomever she can find from the tech department.
Now we ask ourselves: “Which people are the secretary supposed to call?” And we answer with a pronoun: “She is supposed to call them.” Therefore, we use “whomever” in the sentence.
Within a sentence, a verb that has a tense must have a subject; that subject must be in the nominative case.
Any verb with a tense has to have a subject, and therefore the word to use in that situation will be the subjective pronoun “who” or “whoever.” For example:
During the holiday season, I donated money to whoever/whomever was bell-ringing outside of the grocery store.
There are two verbs with tenses in this sentence, and we can check them both for correctness: first, we have “donated,” and the subject is “I”. Then, we have “was bell-ringing,” and there the subject would be “he/she,” so “whoever” is correct. This one may be a little confusing, because we could ask a question, as described above, and get the opposite answer: “Who did I donate money to?” “I donated money to them.” But that leaves the verb “was” without a subject. While rule 1 above will usually get you the correct answer, because “who” vs. “whom” is usually tested in the simpler fashion seen there, if rule 1 and rule 2 produce different answers, you’re probably asking the wrong question. Put simply, rule 2 trumps rule 1 when it’s applicable.
Putting It All Together
Now let’s put it all together with a GMAT-style sentence:
In answer to Jennifer’s query, she was told that in the record store, there is a list of available recordings of lesser-known Jazz artists of whom recordings survive who played at the famous Cat’s Meow speakeasy.
We have two “who” vs. “whom” issues in this sentence, and both can be answered using rules 1 and 2 above. For the first instance, “…Jazz artists of whom recordings survive…” we ask “Which artists are the recordings of?” And the answer is, “The recordings are of them.” Thus, “whom” is correct in the sentence. And then we examine the verb “played,” which is in the past tense. The subject of that verb would be “they,” as in “they played,” which would make the correct pronoun “who.” In this sentence, then, both of those pronouns are used correctly.
Even experienced grammarians sometimes differ on their preferred usages of “who” and “whom,” but these two little rules should be enough to guide you in nearly all instances of “who” vs. “whom” confusion in GMAT sentence corrections.