What book versus which book in Dutch In American English, we usually ask "which book" when given a fixed number of books / choices to select from. For instance, Which book did you buy? Otherwise, we ask.... What book did you buy? Can the same be done with welk and wat in Dutch? For instance, Welke boek heeft hij gekocht? Which book did he buy? And Wat boek heeft hij gekocht? What book did he buy? Also, what about "which books" versus "what books"?