Why do we say "In which" in many formal essays and documents? I never understood this. The definition for which on Merriam Webster is "being what one or ones out of a group". Why is it that we have adapted to using the word 'which' outside of interrogative sentences?
Why do we say "In which"...?
...because "in which" is very much a part of written and spoken English, whether formal or informal. It is simply a prepositional phrase composed of the preposition "in" and the relative pronoun "which." It can be used to mean "where" or "that." Therefore, it can be replaced by the latter two. If you are not comfortable using "in which" try replacing it with where or that, whichever is applicable.
- This is the room 'in which' the supplies were stocked.
- This is the room where in the supplies were stocked.
- The town 'in which' I spent my childhood years is now urbanized.
- The town where I spent my childhood years in is now urbanized. [Notice the in after 'years'.]
- The PC 'in which' the virus was discovered has been transferred to the stock room.
- The PC that the virus was discovered in has been transferred to the stock room. [Notice the "in" after 'discovered'.]
- The subject 'in which' I got the highest score is Math.
- The subject that I got the highest score in is Math. [Notice the "in" after 'score'.]
Well, that's the compromise. You will have to use and place in in appropriate part of the sentence if you opt to use where and that instead of 'in which'.
Why is it that we have adapted to using the word 'which' outside of interrogative sentences?
The relative pronoun 'which' is not only for interrogative sentences. It is also used in statements as in the following ways:
- I shopped at the store which sells trendy dresses and shoes.
- The owner of the car which hit our van did not appear during the mediation.