used instead of ‘who’ as the object of a verb or preposition Whom did they invite? To whom should I write? The author whom you criticized in your review has written a reply. Her mother, in whom she confided, said she would support her unconditionally. Grammar Pointwhom Whom is not used very often in spoken English. Who is usually used as the object pronoun, especially in questions:Who did you invite to the party? The use of whom as the pronoun after prepositions is very formal:To whom should I address the letter? He asked me with whom I had discussed it. In spoken English it is much more natural to use who and put the preposition at the end of the sentence:Who should I address the letter to? He asked me who I had discussed it with. In defining relative clauses the object pronoun whom is not often used. You can either use who or that, or leave out the pronoun completely:The family (who/that/whom) I met at the airport were very kind. In non-defining relative clauses who or, more formally, whom (but not that) is used and the pronoun cannot be left out:Our doctor, who/whom we all liked very much, retired last week. This pattern is not used very much in spoken English.