阅读理解。 I began to send e-mails when I was 17.  I discovered Google 5 years later.  Now, I use the Internet all the time.  Internet has become so popular that 90 percent(％) of 12-to-17-year-olds in the United States use the Internet, and about half of these children use it every day.  They visit chat (聊天) rooms and send e-mails.  They go to websites to get information for their homework. 'Kids are now living in a virtual (虚拟的) world,' says Greenfield, an expert at the University of California, 'As the Internet is becoming more and more important for our life, we should worry about one question: Is the Internet good or bad for kids? ' 'It's difficult to answer the question because the Internet involves (涉及) so many things,' says Justine, who is from Northwestern University.  'They include online computer games, news, messages and even e-mails to your grandmother. ' So, more and more people believe that the online world can be helpful in some ways but dangerous in others. 'Although it's not easy to tell whether it's good or bad,' says Justine, 'the Internet, at least, is very useful and can be used widely by everyone in the world. ' 1.  When did the writer discovered Google ? A.  at the age of 5 B.  at the age of 12 C.  at the age of 17 D.  at the age of 22 2.  What percentage of American 12-to17-year-olds use the Internet every day? A.  About 45%. B.  About 50%. C.  About80%. D.  About 90% 3.  Some ideas about the Internet are mentioned EXCEPT (除了) _____. A. The Internet is a virtual world. B. The Internet is important for our life. C. We can send emails, get news and so on. D. It's not dangerous, so we can look through anything on the Internet. 4.  Which is the best title of the passage? A.  Don't Use the Internet B.  Kids and Emails C.  Is the Internet Good or Bad D.  Two Experts from Universities