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概括大意与完成句子 第四篇 Compact Disks
2014年职称英语真题理工C阅读理解第三篇
If someone says to you your music CDs don't really hold any music on them, and they only have numbers recorded on them, you may not believe it. In fact, he is right in that sound is actually recorded onto the CDs as special numbers ― a digital code.1 The code is pressed onto the CD as bumps on a long spiral track almost five kilometers long. These bumps are an average of 0.5 microns wide.
The light is reflected back to a receiver that records how the laser light bounces back. This lets the CD player2 turn the reflected light back into the original code. This means you can hear the original code as music.
Digital codes are used with many technologies. E-mail needs these kinds of code numbers. Space probes communicate with their ground station on earth using digital codes. Bar codes are read as digital codes in computer systems. Digital communications with cell phones need digital codes. Weather radios also tune into specific signals using these codes.
There are many types of compact disks. One format is called CD-RWs. They can be recorded on and re-recorded on(rewritten on)as you would do with a floppy disk3. Another format is the CD-ROM. The technology for recording on these disks is different from other CDs. These CDs have a dye layer that the CD writer can darken or leave clear. The clear and dark spots are the digital code. CD-ROM stands for Compact Disc ― Read Only Memory4. This disk is like a "super" floppy disk that can hold lots of information. One CD-ROM can hold the same amount of data as 500 floppy disks. Information is permanently recorded onto it. Computer games and other programs are considered to be CD-ROMs.
CDs were first sold to the public in 1982 These CDs still play well and sound fine. Current CDs are expected to last between 70 to 200 years. Of course, you can make sure your CDs last a long time by taking care of them.
Science keeps on developing. It may not be many more years before a completely new technology is invented5 and introduced to the public for music recording. In the meantime, there is no doubt you will continue to enjoy listening to your favorite music on CDs6 and playing your favorite computer games on CD-ROMs.
译文：光盘
如果有人告诉你，你的光盘上实际并没有音乐，有的只是一些录下来的数字，你也许不会相信。但实际上，他说得对，因为其实声音是以特殊的数字形式，即数码，刻录在光盘碟片上。这些数码被强行刻在光盘上，就像一条5公里长的曲折道路上有一些凸起一样。这些凸起平均 0.5微米宽。
当光盘转动时，一束极小的激光射到这些凸起上，光束被反射到接受器上――该接受器是用来记录了激光是如何弹回来的。这样一来，光盘阅读者器就能把反射来的光变成最初的数码。这也就意味着这些最初的数码传到你那里，就成为了你听到的音乐。
数码可用于许多技术。电子邮件依赖这些编码，空间探测器在与地面站联络时也要用到数码。计算机系统可以将条形码读为数码。使用手机进行的数码交流也需要数码。使用这些编码，无线电天气预报设备也可以接受具体的信号。
光盘有许多种。有一种叫做 CD-RW，是一种可反复重刻(重写 )的光盘，其使用原理跟软盘一样。另一种是 CD-ROM，用这种光盘存储数据的技术跟其他的光盘不同。这种光盘有一种染色层，光盘刻录机可以将其涂黑或者留一些空白，这些黑点和空白点就是数码。这里 CD-ROM就是读存储光盘的简称。这种存储盘就如同可容纳海量信息的超级软盘，一张 CD-ROM可以容纳相当于 500张软盘存储的信息，而且上面的信息可以永久保存。电脑游戏和其他程序也可视为 CD-ROM。
人们第一次从市面上购买到光盘是在 1982年，到现在为止这些光盘仍在使用中并且据说效果都还不错。目前人们使用的光盘据说寿命可达 70～200年不等。当然，有一点你可以肯定的是，只要你足够爱惜，你的光盘还可以用得更久。
科学是处在不断发展中的，或许用不了很多年，一种全新的音乐存储形式会为公众所熟识。与此同时，毫无疑问，你将能继续用光盘欣赏你最喜欢的音乐，并且能继续用 CD-ROM玩你最喜欢的电脑游戏。
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