open book片语

坦率的人、一目了然的事

He's an open book; you always know what he's thinking.

他是个坦率的人，你永远知道他在想什么。

未定之事、未知

After graduation, her future is still an open book.

毕业之后，她的前途仍是未定之数。

可查阅书本的、开放式的

Tomorrow's test is open-book, but you still need to prepare.

明天的测验可以翻书，但你还是得准备。