29: E-book is short for electronic( 电子的) book. It is usually read on personal computers. Some mobile phones can also be used to read e-books. Earlier e-books were written for a specific group of readers and were about only a few subjects. With the development of the internet, knowledge and answers to a lot of questions mainly come from e-books. This is why the e-book business is increasing quickly.E-books have many advantages. First, they save time. We don’t need to go to a bookstore to buy books, besides, we can find the topic we want to know about on the Internet, and then we can quickly get many e-books on similar topics. Second, e-books save money. Some e-books cost a little money, and there are millions of e-books on the Internet that we can get for free. Third, more trees are saved because e-books don’t need to be printed(印刷) on paper. Fourth, e-books make reading more convenient. You can carry a whole library of hundreds of books with you in a small computer or any e-book reader (电子阅读器) without worrying about their weight. But e-books have certain disadvantages. They need a personal computer or an e-book reader and the information can be lost if its file format (文件格式) is not supported or changed in the reader’s computer. However, e-books provide us with a new way of reading. That is good.