To which, in which etc.consist of a
preposition and a
relative pronoun. The preposition is usually determined by a verb, noun or adjective. In informal style the preposition is often placed at the end of the relative clause. Examples:
This is the house in which he lives. This is the house [which/that] he lives in.
The preposition is in because that preposition is used with house in this context and meaning: He lives in this house.
I bought the book about which you told me yesterday. I bought the book [which/that] you told me about yesterday.
The preposition is about because that preposition is used when we tell somebody about something: He told me about his problems.
Where is sometimes possible instead of to which or in which, especially when the intended meaning is that the place of something is mentioned:
Take this kettle to the kitchen where it belongs.
But: Ages ago, this island was occupied by Great Britain, to which it belongs even now / which it belongs to even now.
Note that there is a comma in the last sentence. A comma is needed for a certain type of relative clauses. Use the Search box to find out more about them.
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