职称英语理工类考试考前每日一练(4)

　　职称英语理工类考试考前每日一练

　　Compact Disks

　　1 If someone says to you your music CDs dont 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 numbersa digital codel。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 bearn shines onto the bumDs 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.Email needs these kinds of code numbers.Space probes cornmunicate with their ground station on earth using digital codes.Bar codes are read as digital codes in computer systerns.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 CDRWs.They can be recorded on and rerecorded onas you would do with a floppy disk3.Another format is the CDROM。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.CDROM stands for Compact DiscRead Only Memory4。This disk is like asuperfloppy disk that can hold lots of information.One CDROM 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 CDROMs.

　　5 CDs were first sold to the public in l982.These CDs still play well and sonnd 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 CDROMs.

　　词汇：

　　bump n.隆块，隆起 floppy disk软盘

　　spiral adj.螺旋形的 format n.格式

　　probe n.探测器dye n.染色

　　floppy adj.松软的Permanently adv.永久地

　　注释：

　　1.he is right in that sound is actually rdcorded onto the CDs as special numbersa digital code：他说的对，因为实际上声音以特殊的数字的形式，即数码，刻录在CD碟片上。in that是因为，如：Water is essential in that without it all living things would die.

　　2.CD player：CD播放机

　　3.as you would do with a floppy disk：就象你使用软磁盘一样

　　4.CDROM stands for Compact DiscRead Only Memory：CDROM是Compact DiscRead Only Memory这五个词首字母的组成的缩写词。

　　5.It may not be many more years before a completely new technology is invented：过不了几年，说不定又会发明一种全新的技术。many more years是再过许多年。

　　6.there is no doubt you will continue to enjoy listening to your favorite music on CDs语法上可以理解为there is

　　no doubtyou will continue to enjoy listening to your favorite music on CDs。

　　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.CDs working principle is explained.

　　E.CD-RWs play better than CDROMs.

　　F.CDs are of many formats.

　　5.One advantage of CDRWs is that they ean____like floppy disks。

　　6.The author predicts it will not____before a new technology is invented for music recording.

　　7.The laser beamemitting 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