Telephone lines were designed to carry the human voice, not electronic data from a computer. Modems were invented to convert digital computer signals into a form that allows them to travel over the phone lines. Those are the scratchy sounds you hear from a modem's speaker. A modem on the other end of the line can understand it and convert the sounds back into digital information that the computer can understand. By the way, the word modem stands for MOdulator/DEModulator.
电话线是用来传输人们的声音而非计算机中的电子信号的。发明调制解调器是为了将数字计算机信号转换成一种允许它们在电话线路中传输的形式。那些就是你从调制解调器的扬声器中听到的“沙沙”声。在电话线另一头的调制解调器可以“听懂”并将声音还原成计算机能够理解的数字信息。顺便说一下，调制解调器表示调制器/解调器。
.About Modem 关于调制解调器
(1).Speed It Up 加速
(2).Cable Modems 凯布尔调制解调器考研空间
(3).DSL 数字用户专用线
2.The NetWorks 网络考研空间
(1).Birth of the Net 网络的诞生
(2).How the Web Works 网络是如何工作的
(3).Some Web History 一些网络的历史
计算机英语论文New technique of the computer network
计算机英语教学目标