1. Chemistry is a closed book to me.

2. Mathematics has always been a closed book to me.

3. Economics was a closed book to him.

4. I'm afraid physics will always be a closed book to me.

5. Nuclear physics is a closed book to most of us.

6. I'm afraid geophysics is rather a closed book to me.

7. The Shoah will never be a closed book.

8. The kitchenette is a closed book.

9. He is holding a closed book, signifying a mystery, possibly a stage in the alchemical process.

10. Linear preoccupation in the past remains a closed book to modern understanding.

11. But your own past can be a closed book, even at fourteen.

12. I tell myself it's a closed book, but my cover story becomes an old man's compensation.

13. Talbot slid his closed book into his satchel.

14. Nuclear physics is a closed book to me.

15. Qualification exam practice computer test, using closed book.

16. The actress'life a closed book to us.

17. The man's early life is a closed book.

18. Philosophy is a closed book to me.

19. Fishing is closed book to me.

20. For me, geology is a closed book.

21. For many people the Bible is a closed book.

22. Mathematics is a closed book to me (http://sentencedict.com), I'll never understand it.

23. A closed mind is like a closed book; just a block of wood.

24. Hold the CLOSED book in your hand on your lap or on a table.

25. Frank Spriggs was a very able man but something of a closed book.

26. I'm not sure what is worse, a closed mind or a closed book. Anthony Liccione 

27. I can not believe that it can be right that this late in the game Poetry is still a closed book.

28. The highly organised St Stephen's Society programme which she now leads was at that time a closed book to her!

29. My wife used to say I a hard man to know. Like a closed book.

30. Andy: My wife used to say I a hard man to know, like a closed book.