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參考原文：

　　1　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.

　　2　A small laser beam shines onto the bumps as the CD turns. 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.

　　3　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.

　　4　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.

　　5　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.

　　6　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.

　　詞匯：

　　bump / bʌmp/ n.隆塊，隆起

　　spiral / ’spaɪərəl / adj.螺旋形的

　　probe / prəʊb/n.探測器

　　floppy / ’flɒpɪ/ adj.松軟的

　　floppy disk軟(磁)盤

　　format / ’fɔ:mæt/ n.格式

　　dye / daɪ/ n.染色

　　permanently / ’pɜ:mənəntlɪ / adv.永久地

　　注釋：

　　1.... he is right in that sound is actually recorded onto the CDs as special numbers – a digital code：他說的對，因為實際上聲音以特殊的數字形式，即數碼，刻錄在CD碟片上。in that是“因為”，如：Water is essential in that without it all living things would die.水是基本要素，因為沒有水，所有生物都要死亡。

　　2.CD player：CD播放機

　　3.as you would do with a floppy disk：就像你使用軟磁盤一樣

　　4.CD-ROM stands for Compact Disc – Read Only Memory：CD-ROM是Compact Disc – Read Only Memory這五個詞首字母組成的縮寫詞。

　　5.It may not be many more years before a completely new technology is invented：過不了幾年，說不定又會發明一種全新的技術。many more years是“再過許多年”。

　　6.“there is no doubt you will continue to enjoy listening to your favorite music on CDs”語法上可以理解為“there is no doubt(about the fact that)you will continue to enjoy listening to your favorite music on CDs”。

　　練習：

　　A　Digital Code Has Wide Applications

　　B　Floppy Disks Are Outdated

　　C　CDs Are Durable

　　D　CD's Working Principle Is Explained

　　E. CD-RWs Play Better Than CD-ROMs

　　F. CDs Are of Many Formats

　　1. Paragraphs l & 2 ________

　　2.Paragraph 3 ________

　　3.Paragraph 4 ________

　　4.Paragraph 5 ________

　　5.One advantage of CD-RWs is that they can ________ like floppy disks.

　　6.The author predicts it will not ________ before a new technology is invented for music recording.

　　7.The laser beam-emitting device and the receiver are considered to ________ of a CD player.

　　8. Space probes could not ________ without using digital codes.

　　A　shine on bumps

　　B　take many more years

　　C　be the key parts

　　D　restore the original code

　　E　be written on and rewritten on

　　F　keen contact with their ground station efficiently

　　第四篇：Compact Disks

　　答案與題解：

　　1.D　第一、二段介紹了CD的工作原理。聲音以數碼的形式刻錄到CD碟片上。要想聽聲音,就得用CD放音機，CD機用激光照射CD，接收器接收和分析從CD反射回來的激光波，還原為原來的數碼，再轉換為原來的聲音。所以，D是答案。

　　2.A　第三段第一句“Digital codes are used with many technologies.”是主題句。本段其他句子提供例證，即應用領域。作者列舉了五個領域：電郵、航天通訊、條碼、手機和天氣預報。選項A的“Digital code has wide applications”與主題句的意思完全吻合，所以是答案。

　　3.F　第四段第一句“There are many types of compact disks.”是主題句。本段其他句子列舉了兩種常用的CD格式(format)：—種是CD-RW，另一種是CD-ROM。選項F的“CDs are of many formats”概括了本段的大意，是答案。

　　4.C　第五段說的是CD碟片經久耐用，1982年上市的CD碟片至今還能使用，其音質依舊。現在上市的CD，更加耐用，如果使用得當，其壽命可達70 ~ 200年。選項C用了durable予以概括是很恰當的，所以，C是答案。

　　5.E　第四段中出現CD-RW這個詞，介紹了They can be recorded on and re-recorded on(rewritten on)。這就是選E的依據。

　　6.B　第六段能找到與答案有關的句子，即It may not be many more years before a completely new technology is invented and introduced to the public for music recording.

　　7.C　第二段說到在CD機上還原數碼時依靠的是激光發射裝置和接收器。由此我們可以推論出激光發射和接收器是CD機的主要部件。所以C是答案。

　　8.F　第三段第三句“Space probes communicate with their ground station on earth using digital codes.”是選F的依據。