In recent years, people are developing an inseparable relationship with the Internet. As is vividly depicted in the picture, it is convenient for us to click the mouse when surfing on-line, either to entertain ourselves or to meet the work's needs. Actually surfing the Internet has become a daily routine in our life. However, it seems rather ironic to use a chain instead of a cord to connect with the mouse in this picture. The exaggerative and impressive portrayal has subtly revealed the duality of the relationship between man and Internet. Discussions on the duality become very popular in newspapers or in people's chats. On the one hand, no one denies that Internet is currently one of the most useful media in our daily life. People from all walks of life are benefiting considerably from its powerful function of information communication. As a college student, I get on-line every day to read the news, to study English by registering for web courses, to exchange information with my net friends through e-mails and to download my favorite music, flash, film and pictures.