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 didn't work well. If one computer in the network broke down， then the whole network stopped. So a few network system 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 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， but in the early 1970s， universities， hospitals and banks were allowed to use it， too. However， computers were still very expensive and the Internet was difficult to use. By the start of 1990s， computers became cheaper and easier to use. Scientists had also developed software that made "surfing" the Internet easier.

    Today it is easy to get online and it is said that millions of people use the Internet every day. Sending e-mails is more and more popular among young people. The Internet has now become one of the most important parts of people's life.

背诵默写。
①_____________，到乡翻似烂柯人。（刘禹锡《酬乐天扬州初逢席上见赠》）
②中军置酒饮归客，__________。（岑参《白雪歌送武判官归京》）
③《山坡羊 潼关怀古》中交代潼关地理位置险要的诗句是：__________。
④《小石潭记》中描写水的句子很多。其中，以奇特的想象间接表现潭水清澈的语句是：__________；直接描写溪水形状的语句是：__________。

《咏华山》是宋朝宰相____七岁时作的，他是这样歌咏的：只有天在上，更无山与齐。 举头红日近，____。

△ A B C与 $\Delta A\text{'}{B}^{\prime }{C}^{\prime }$ 在平面直角坐标系中的位置如图.