In the absence of a clear context regarding how known or unknown is the number of books available for me to read, should I use what book to read or which book to read?

I don't know what book to read (= I don't know how many books there are for me to choose from.)

I don't know which book to read (= I know how many books there are for me to choose from, and choose one from that specified number.)

Are these assumptions correct or not? If not, why?

"what book" is quite a general question. In a bookshop the shop assistant might ask "What (kind of) book do you want? A novel, a garden book, a children's book and so on?

"which book" is always asking with reference to a special group of books. When the shop assistant points at a table with a lot of books, he might ask "Which book do you want to see?". He might as well ask "Which of these books do you want to see?"

protected by MetaEd Jun 27 at 21:25

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