Breakdown of Le document n'est pas parmi le tas, mais entre les livres.
être
to be
mais
but
le livre
the book
ne
not (used before the verb)
Questions & Answers about Le document n'est pas parmi le tas, mais entre les livres.
Why do we use parmi for the pile, but entre for the books?
This highlights the exact difference between these two prepositions. Parmi means 'among' a general group where the items aren't viewed individually. Entre means 'between,' highlighting the physical space separating distinct items. The document isn't just lost in the general pile (parmi le tas); it is physically sandwiched between individual books (entre les livres).
I thought parmi had to be followed by a plural noun. Why can we say parmi le tas?
It is true that parmi is usually followed by a plural noun (like parmi mes amis). However, you can use a singular noun if it is a collective noun—a single word that represents a group of things or people. Because le tas (the pile) implies a collection of multiple objects, using parmi here is completely correct.
Would it be wrong to say parmi les livres?
I have seen the word tas used differently before. Can it mean something other than a literal pile?