To make e-book readers you don't have to cut down trees, and they can be reused. They can be loaded with several textbooks at the beginning of each term, and new teaching materials can be added according to learning needs, by downloading from the Internet. The saving in printed books makes the devices extremely environmentally friendly.
電子書不用砍樹，還可以重複使用，一學期可以輸入幾本書，然後利用網路上網，隨時加入新教材配合教學，非常環保。