Run-on sentencfes and comma splices

1. An encyclopedia is a valuable source of information it contains summaries of every area of knowledge.

2. Because of the rapid expansion of human knowledge, it is difficult to keep encyclopedias current.

3. A printed encyclopedia becomes obsolete almost as soon as it is published also it is quite expensive to purchase.

4. Encyclopedias on CD-ROMs are inexpensive, convenient to use, and easily updated.

5. Articles in encyclopedias are written by experts in each subject, who are often university professors.

6. An editor of an encyclopedia doesn't write articles he only collects and edits articles written by other experts.

7. To find a book on a certain subject, you used to look in a cart catalog, to find a magazine article on a subject, you used to look in a periodical index.

8. Now, most libraries have thrown away their card catalogs, they have computerized catalogs that are much more efficient to use and update.

9. Many periodical indexes, which only list titles of magazine articles and indicate where to find them, have been replaced by computer indexes, some of which display synopses and even entire articles instantly.

10. If you can't find any information on a subject, you can always ask a librarian to help you, they are paid to assist students.

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