English version

a closed book (to somebody)

From Longman Dictionary of Contemporary Englisha closed book (to somebody)a closed book (to somebody)NOT KNOWa subject or problem that someone does not know about or understand Mathematics has always been a closed book to me. closed
Examples from the Corpus
a closed book (to somebody)I can not believe that it can be right that this late in the game Poetry is still a closed book.The kitchenette is a closed book.The Shoah will never be a closed book.I tell myself it's a closed book, but my cover story becomes an old man's compensation.But your own past can be a closed book, even at fourteen.He is holding a closed book, signifying a mystery, possibly a stage in the alchemical process.The highly organised St Stephen's Society programme which she now leads was at that time a closed book to her!Linear preoccupation in the past remains a closed book to modern understanding.
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