[Ask ] a grammatical problem with preposition

[theundertake (joker)]

Hello! Everybody!
I am a man who is studying English for ielts test.
As the title, I have a grammatical problem on an issue as below.


Caesarean n.

an operation in which a woman's womb is cut open to allow a to be born.


It's clearly that the pronoun of this sentence is which, and my question is which is the related "verb" to the preposition "in" before the pronoun?

I really appreciate the help you would give me!


P.S. if anybody is looking for a partner to practice oral test each other, message me plz!
Actually I just got a failure on my test, so you want to reach a high score, I am afraid I can't help you :p




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→ netpchome: could you give us a whole sentence for it?
→ EmptyCooker: It is not a sentence, but a noun clause to
→ EmptyCooker: explain what "Caesarean" is. So it hase no verb.
→ EmptyCooker: It is quite usual in dictionary. If you really
→ EmptyCooker: to know where is the "verb". Just put "It is"
→ EmptyCooker: before the clause "an operation", and the verb is
→ EmptyCooker: "is".
→ theundertake: sorry for my late reply, I can understand now,
→ theundertake:  in which is relative adverb