Prepositions in Relative Clauses
B2-C1 Level
When a relative clause contains a preposition, there are two positions it can take.
In informal English, the preposition stays at the end: "The person
who I spoke to" or "The house that I live in." In
formal English, the preposition moves before the pronoun: "The person
to whom I spoke" or "The house in which I live." Both are grammatically
correct, but the formal version is expected in academic writing and advanced exams.
When you move the preposition forward, two important changes happen. First, for people, you must use whom (not "who"): "to whom," "with whom," "for whom." Second, for things, you must use which (not "that"): "in which," "about which," "for which." You can never use "that" directly after a preposition — "the topic about that we discussed" is wrong. In Cambridge B2 First and C1 Advanced exams, sentence transformation tasks often require you to change informal preposition-final structures into formal preposition-fronted ones, so practising both positions is essential.
When you move the preposition forward, two important changes happen. First, for people, you must use whom (not "who"): "to whom," "with whom," "for whom." Second, for things, you must use which (not "that"): "in which," "about which," "for which." You can never use "that" directly after a preposition — "the topic about that we discussed" is wrong. In Cambridge B2 First and C1 Advanced exams, sentence transformation tasks often require you to change informal preposition-final structures into formal preposition-fronted ones, so practising both positions is essential.
Quick Rule
informal: who/which/that ... preposition | formal: preposition + whom (people) / which (things)
- 1.The colleague to whom I sent the email has not replied. (formal — preposition before whom)
- 2.She raised a topic about which they argued for hours. (formal — preposition before which)
- 3.That's the school which I went to as a child. (informal — preposition at the end)
- 4.The reason for which she resigned was never made public. (formal — preposition before which)
- 5.I don't know the person with whom he was speaking. (formal — preposition before whom, negative)
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