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the library of my adolescence in buenos aires contained almost every book that still matters to me today. generous teachers, passionate booksellers, friends for whom giving a book was a supreme act of intimacy and trust, helped me build it. their ghosts kindly haunt my shelves and the books they gave still carry their voices. i have the impression not of reading the book myself but of being read to. this is one of the reasons i never feel alone in my library.

밑줄 친 관계대명사 whom 앞에 왜 for이 들어가주었나요??? whom이라면 목적격 관계대명사라는 건데.... 저 문장 친절한 문법 설명 좀부탁드리겠습니다.
ㅜㅠㅜㅠ