How does one correctly apply “in which”, “of which”, “at which”, “to which”, etc.?

I'm confused with which one to apply when constructing sentences around these.


2 Answers 2


The trick to knowing how to use; of which, at which, in which, to which, from which is to analyse the prepositional phrases, phrasal verbs, verbs and prepositions:

  1. He /spoke of/ war and peace and many other topics that day.
    The topic /of which he spoke/ was complex.
    The verb here that means to speak about a topic is /to speak/ of a topic/: to mention

  2. The party /at which/ he spoke/ was noisy.
    Phrase: A party is held /at a place/. It is implied.
  3. The situation /in which/ we found ourselves was dire.
    Phrase: /to find oneself /in a situation.
  4. The bonds /from which/ we broke free were tight.
    phrase: to /break free/ from bonds.
  5. The town /to which/we were driving was 50 ks away.
    phrase: to /drive/ to a place.

Summary (and not a complete answer but a general one): The preposition depends on the verb that takes a preposition, a phrasal verb that includes a preposition, or it depends on the prepositional phrase used. Also, there are many other prepositions that can be paired with which: under, during, about, over, etc.

  • What's the difference between "The topic he spoke were complex." vs "The topic /of which he spoke/ were complex"?
    – Pacerier
    Feb 7, 2017 at 11:14
  • And also "The town which we were driving to was 50 ks away" vs "The town /to which/we were driving was 50 ks away".
    – Pacerier
    Feb 7, 2017 at 11:17
  • @Pacerier /The topic he spoke/ is not grammatical/idiomatic. To speak ON or OF or ABOUT a topic. All with different meanings. In the second sentence the only difference is informality/spoken English versus more formal/written English
    – Lambie
    Feb 7, 2017 at 13:36
  • 1
    @Mr. Hyde One can sometimes shift the preposition in writing or in speech, yes: "the party which he spoke at was" etc.. Bear in mind, though, that in non-literary writing, the preposition would not be shifted. Which without in is not part of this question. The point here is about the prepositioins.
    – Lambie
    Mar 17, 2018 at 13:31
  • 1
    @deadManN Yes, that's fine and it is a completely different question, in fact. My answer is about which preposition to use, not where to place it....
    – Lambie
    May 14, 2020 at 20:50

Probably easiest to explain through examples. Each phrase simply means "the thing that we've already mentioned", e.g.

  • The box in which the books are kept

  • The town of which we were speaking

  • The time at which we will arrive

  • The destination to which we were heading

I'm sure there's a grammatically-correct term, but they're really just the correct forms of "the box the books are kept in"/"the town we were speaking of", i.e. removing the trailing preposition.

  • 1
    I've seen them called a 'complex relative phrase', in contrast to a 'simple relative phrase' which consists of a relative word on its own (e.g. "which", "who", "why" etc.)
    – BillJ
    May 1, 2016 at 17:30
  • The point is to know which preposition to use: in, of, about, in, under, over, etc. You are not answering the question. speak of a matter, of which; fall under a statute, under which, arrive at a time, at which. And so forth.
    – Lambie
    Nov 17, 2018 at 13:45

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