1. We are all busy talking about and using the Internet (因特网), but how many of us know the history of the Internet? Many people are surprised when they find that the Internet was set up in the 1960s. At that time, computers were large and expensive. Computer networks (网络) didn＇t work well. If one computer in the network broke down, then the whole network stopped. So a new network system (系统) had to be set up. It should be good enough to be used by many different computers. If part of the network was not working, information（信息）could be sent through another part. In this way computer network system would keep on working all the time. At first the Internet was only used by the government (政府), but in the early 1970s, universities (大学), hospitals and banks (银行) were allowed (允许) to use it too. However, computers were still very expensive and the Internet was difficult to use. By the start of the 1990s, computers became cheaper and easier to use. Scientists had also developed software (软件) that made "surfing" (浏览) the Internet more convenient (方便).Today it is easy to get on-line (上网) and it is said that millions of people use the Internet every day. Sending e-mail (电子邮件) is more and more popular among students. The Internet has now become one of the most important parts of people＇s life. The Internet has a history of more than ___ years.