Closed book
01
閉じた本, 謎
someone or something one knows very little or nothing about
Idiom
Informal
例
The workings of the stock market are a closed book to me – I do n't understand how it works.
株式市場の仕組みは私にとって未知の領域です–どのように機能するのか理解できません。
The new technology is a closed book to most people – they're not familiar with it yet.
新しい技術はほとんどの人にとって未知の領域です–彼らはまだそれに慣れていません。
