be an open bookKNOW somethingto be something that you know and understand very well 是…非常熟悉的事物,是…很了解的事物 The natural world was an open book to him. 他对自然界了如指掌。
be an open book• I'd always thought of Jeff as an open book.• To them my future was an open book.• Our foreign dealings are an open book generally a check book.
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