So one time is quyen sach and one time it's con sach... and they sound nearly the same... how do you know which to use?
I also have this question. Are they interchangeable? Or, is one for plurals and one is for singular forms?
Should also allow "chúng tôi đọc sách" for generic books, as the sentence implies.
Apart from whatever this means in Vietnamese, the use of the article makes a meaningful difference in English.
"Quyển sách" and "cuốn sách" are interchangeable, but "cuốn sách" was marked incorrect as of this comment.
Cuốn sách = Quyển sách