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【简答题】
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 (iEfeJ^), 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.
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举一反三
【单选题】液压元件可分为动力元件、执行元件、()、辅助元件。
A.
控制元件
B.
操作元件
C.
执行元件
【简答题】一般液压执行元件分为液压缸和 两类。A. 液压马达
【判断题】液压传动系统一般由下列元件:动力元件、执行元件、控制元件、辅助元件和工作元件组成。()
A.
正确
B.
错误
【判断题】任何复杂的物体,仔细分析起来,都可看成是由若干个基本几何体组合而成的。()
A.
正确
B.
错误
【单选题】凝聚过程通常在()中完成。
A.
混合器
B.
絮凝池
C.
溶药箱
【判断题】液压传动元件中,液压缸属于执行元件。()
A.
正确
B.
错误
【判断题】苗青通过贿赂,成功逃脱罪责,事件的参与者都从他那里获得了好处。
A.
正确
B.
错误
【多选题】肝血窦的结构特征是
A.
内皮细胞为连续型
B.
位于肝板之间
C.
血窦腔与窦周隙互不相通
D.
内皮外无明显的基膜
E.
窦壁上附有肝巨噬细胞
【单选题】换向阀不能达到以下的功能( )。
A.
液压执行元件启动
B.
液压执行元件停止
C.
液压执行元件变换方向
D.
液压执行元件加速
【单选题】不属于箭头所指结构特点的是:
A.
位于肝细胞与血窦内皮细胞之间
B.
含血浆
C.
含巨噬细胞
D.
含储脂细胞
E.
含网状纤维
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