9. There are 35 books in total on a bookshelf, including storybooks, science books, picture books, and dictionaries, with each type of book having a different number of copies. Among them, storybooks and science books total 17 copies, and science books and picture books total 16 copies. One type of book has 9 copies, so this type of book is $\qquad$.
【Analysis】There are 18 books in total of albums and dictionaries, so it cannot be albums and dictionaries. If there are 9 storybooks, then there would be 8 science books, which conflicts with 8 albums; If there are 9 science books, 8 storybooks, 7 albums, and 11 dictionaries, it meets the requirements, so it is the science book.