meaning of "I'm a closed book"

[storm]

What does it mean and please give me sample sentences?

Thanks a lot !
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There are always things I have to learn.

[Yankee]

Hi Storm

Is the sentence "I am a closed book" your sentence or did you read it somewhere? If you read it somewhere, what was the context?

We sometimes say that a person is an "open book", which means that it is easy to understand, to know, or to discover information about that person.

So, your sentence "I am a closed book", seems to mean "I am not easy to understand". However, depending on the context, there may be other ways of interpreting that sentence.

It would be more common to say that a certain topic (rather than a person) is a "closed book to me", and that means that the topic is something that you don't know anything about or that the topic is a complete mystery to you.

"Pharmacokinetics is a closed book to me. I know nothing about it."
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Amy
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ESL teacher, translator, and a native speaker of American English

[storm]

Well Ami, I was asked this sentence by my engineer student at the hotel. He was trying to sign up in a dating website and I reckon this is a kind of drop down menu to choose what kind of person one is? Only a short phrase "a closed book". This is very new to me so I asked for help here then.

Thank you very much for your good explaination as always.
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There are always things I have to learn.

[Forastero]

There's a similar sentence in spanish

Perhaps it means that you can hear (listen?) someone's secret, and you won't tell to someone else. You're a Book (because you have information) but you're closed (Because no one can know this information)

What do you think of it?
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Alijunakai, my blog in spanish