American, using which in restrictive clauses is avoided where possible (see that or which below). whom is used only when its antecedent is the object of the relative clause, but not when its antecedent is the subject of the clause ("The officer nabbed the thief whom I saw")antecedent thief is the object of the relative clause; but not ("The officer nabbed the thief whom saw me")here the antecedent thief is the subject of the relative clause ("... the thief _ saw me"); who is correct here. When a preposition in the relative clause is placed in front (fronted), only whom or which is used ("The waiter to whom I spoke", or "The putter with which she wins"), and never acceptable is who (“The waiter to who I spoke”) or that ("The putter with that she wins"). With informal style the preposition is often dangled (or stranded), not fronted, and who and that may also be used (“The mailman who I spoke to”, “The mailman that I spoke to”, as well as “The mailman whom ...”); and (“The putter that she wins with”, or “The putter which ...”), or the zero relative pronoun is frequently used (“The putter she wins with”). (See Zero relative pronoun). When that is used in a restrictive relative clause and it is not the subject of the relative clause, it may be omitted entirely. For example: ("The dentist that I saw" or "The dentist that I spoke to") may be rendered simply ("The dentist I saw" or "The dentist I spoke to"). But any relative pronoun when used in a non-restrictive relative clause must not be omitted ("My dentist, whom I saw", or "My dentist, who spoke to me"); nor when its preposition is fronted ("The dentist to whom I spoke"); nor when its antecedent is the subject of the relative clause ("The dentist that saw me”, or “The dentist who saw me"). The verb in a relative clause takes the same person (first, second, or third) and number (singular or plural) as that of the antecedent of the relative pronoun. In ("The people who were present ...") the antecedent of who is people (third person, plural), so the verb to be takes its form (were) for third person and plural number; in ("I, who am normally very tolerant, ...") who‘s antecedent is the pronoun I (first person, singular), so the verb to be takes its