1. The film, which I watched on TV last night, was interesting.
2. The flat, in which my family used to live, was very old.
3. The birthday party, to which we went, was too noisy.
4. Who was that boy with whom you were this morning?
5. I don't like the tie which John was wearing.
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* Who: Thay thế N chỉ người ở vị trí chủ ngữ
* Whom: Thay thế N chỉ người ở vị trí tân ngữ
* Which: Thay thế N chỉ vật, làm tân ngữ hoặc chủ ngữ
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