YOU SAID:
Did he not know what book to bring to the office?
INTO JAPANESE
彼はどの本をオフィスに持っていくべきか知らなかったのですか?
BACK INTO ENGLISH
Didn't he know which book to bring to the office?
INTO JAPANESE
彼はどの本をオフィスに持っていくべきか知りませんでしたか?
BACK INTO ENGLISH
Didn't he know which book to bring to the office?
That didn't even make that much sense in English.