单选题 The card catalog is a catalog of all the books in a library. Every book has at least three cards: an author card, a title card, and one or more subject cards. If you need a book by a particular author, look in the author catalog. If you know the title of the book you need, look in the title catalog. If you need a book on a particular subject, look in the subject catalog.
Every card contains a lot of basic information about the book such as the topics covered. If you learn to read the cards, you won"t waste time looking for books that you cannot use.
The most important thing to look for on the card is the date of publication. An engineering book published in 1898 is probably not worth finding. Next, look at the bottom of the card for the subjects under which the book is cataloged. Do they seem relevant to your topic? Now look for the total number of pages in the book. The length may help you decide whether it is worth your time to find the book and read it. Finally, look for the word "Bibliography" (文献目录), often written as "Bibliography", on the card. If a book is relevant to your subject and contains a bibliography, it is worth checking. The bibliography will lead you quickly to other relevant sources of information.