概括大意与完成句子
Compact Disks
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. 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 player 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 in to 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 disk. 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 Memory. 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 invented 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 CDs and playing your favorite computer games on CD-ROMs.
1、1. Paragraphs 1 & 2 _____
2. Paragraph 3__________.
3. Paragraph 4__________.
4. Paragraph 5__________.
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B. Floppy disks are outdated.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.
【正确答案】 DAFC
【答案解析】 1. D
本题是问第一段和第二段的主旨大意。通过阅读第一段和第二段，可以明显的看出来，这两段是在解释CD的工作原理的，从a digital code到sound的发出，因此本题应该选D，即“解释CD的工作原理”。
2.A
通过第三段的第一句话：Digital codes are used with many technologies.可以得出，本段是在阐述digital codes的广泛用途的。紧接着，用不同的实例去说明digital codes的用途。
3.F
同理，本题的答案也可以从段落的首句得出：There are many types of compact disks.是说，CD有多种类型，多种格式，如：CD-RWs，CD-ROM等。故选F。
4.C
第五段段落很短，但每句都是在说CD使用的年限很长，比较耐用，即These CDs still play well and sound fine. Current CDs are expected to last between 70 to 200 years.因此本题的答案为C，durable表示“经久耐用的”。
2、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. keep contact with their ground station efficiently
【正确答案】 EBCF
【答案解析】 5.E
本题可以从第四段的第二句话找出答案：One format is called CD-RWs. They can be recorded on and re-recorded on (rewritten on) as you would do with a floppy disk. 尤其是括号里给出的单词，根据同义重现，因此选E。
6.B
本题也是细节题，可以从最后一段的第二个句子得出答案：It may not be many more years before a completely new technology is invented and introduced to the public for music recording.很明显，原句复现，答案为B。
7.C
本题从原文中是找不到原句和答案的，属于总结概括题。主要依据是第一段和第二段，CD的工作原理涉及到The laser beam-emitting device and the receiver，它们是CD运行不可或缺的装置。观察选项，通过逐一排除，选项C. be the key parts是符合题意的，即“CD的关键装置。
8.F
本题可以从第三段的第三句得出答案：Space probes communicate with their ground station on earth using digital codes. 航天探测器需要用数码与地面卫星接收站进行联系沟通，因此没有digital codes，就不能有效的进行沟通，故答案为F。
