Whom

Whom \hoom\ , pronoun;
1. The objective case of who
2. The dative case of who

First, the proper way to use who and whom:Both words are pronouns, but who is a subject and whom is an object. So, if your answer is he or she the question word is who. If your answer is him or her use who. That's confusing, so here's an example:
     Who invited Jerry? He invited Jerry.
     Jerry was invited by whom? Jerry was invited by her.

Got it? If not, don't worry about it. It's not really important anymore unless you are a hard-core grammar type, or if someone grading your papers is. This sort of thing (like shall) is a grammar technicality that comes up in the prescriptive v. descriptive debate. Prescriptive grammar is what you are taught in school: 'proper English'. You know, don't split infinitives, don't start sentences with and, etc. Descriptive grammar is the way people really speak. Elisions like gonna and wanna sprinkle oral English, along with abominations like, "Where are you going? I wanna come with." (The error is ending a sentence with a preposition, but you already knew that). Generally speaking, linguists are more concerned with descriptive language because that's the most common way that language is used. Writers, editors, and English teachers are more concerned with prescriptive grammar because 'proper English' is the lingua franca of written language.