每日一练：职称英语考试卫生类每日一练(2018/12/23)
【单选题】
Compact Disks
1 If someone says to you your music CDs don’t really hold any music on them, and they only have numbers recordedon them, you may not believe it. In fact, he is right in that sound is actuallyrecorded onto the CDs as special numbers — a digitalcode.1 The code is pressed onto the CD as bumps on a long spiral track almostfive kilometerslong. These bumps are an average of 0.5 microns wide.
2 A small laser beam shines onto the bumps asthe CD turns. The light is reflected back to a receiver that records how thelaser light bounces back. This lets the CD player2 turn the reflected lightback into the original code. This means you can hear the original code asmusic.
3 Digital codes are used with manytechnologies. E-mail needs these kinds of code numbers. Space probescommunicate with their ground station on earth using digital codes. Bar codesare read as digital codes in computer systems. Digital communications with cellphones need digital codes. Weather radios also tune in to specific signalsusing these codes.
4 There are many types of compact disk. Oneformat is called CD-RWs. They can be recorded on and re-recorded on (rewrittenon) as you would do with a floppy disk3. Another format is the CD-ROM. Thetechnology for recording on these disks is different from other CDs. These CDshave a dye layer that the CD writer can darken or leave clear. The clear anddark spots are the digital code. CD-ROM stands for Compact Disc — Read Only
Memory.4 This disk is like a “super” floppy disk that can hold lots ofinformation. One CD-ROM can hold the same amount of data as 500 floppy disks.Information is permanently recorded onto it. Computer games and other programsare 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 expectedto lastbetween 70 to 200 years. Of course, you can make sure your CDs last a long timeby taking care of them.
6 Science keeps on developing. It may not bemany more years before a completely new technology is invented5 and introducedto the public for music recording. In the meantime, there is no doubt you willcontinue to enjoy listening to your favorite music on CDs6 and playing your favoritecomputer games on CD-ROMs.
练习:
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B Floppy Disks Are Outdated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 WorkingPrinciple Is Explained
E CD-RWs Play Better Than CD-ROWs
F CDs Are of Many Formats
5. One advantage of CD-RWs is that they canlike floppy disks.
6. The author predicts it will not before a newtechnology is invented for music recording.
7. The laser beam-emitting device and the receiverare considered to of a CD player.
8. Space probes could not without using digitalcodes.
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在下面提交答题后即可查看答案与试题解析
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