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页数:9页
时间:2019-10-18
《职称英语等级考试理工AB精讲班课程(11)第十一讲阅读判断》由会员上传分享,免费在线阅读,更多相关内容在工程资料-天天文库。
1、职称英语等级考试理工AB精讲班课程第十一讲阅读判断>阅读判断例题解析:ComputermouseThebasiccomputermouseisanamazinglycleverinventionwitharelativelysimpledesignthatallowsustopointatthingsonthecomputeranditisveryproductive.Thinkofal1thethingsyoucandowithamouse1ikeselectingtextforcopyingandpasting,drawing,ande
2、venscrollingonthepagewiththenewermicewiththewheel.Mostofususethecomputermousedai1ywithoutstoppingtothinkhowitworksunti1itgetsdirtyandwehaveto1earnhowtocleanit.Welearntopointatthingbeforewelearntospeak,sothemouseisaverynaturalpointingdevice・Othercomputerpointingdevicesinclu
3、delightpens,graphicstabletsandtouchscreen,butthemousestillourworkhorse.Thecomputermousewasinventedin1964byDouglasEnglehartofStanfordUniversity・Ascomputerscreensbecamepopularandarrowkeyswereusedtomorearoundabodyoftext,itbecameclearthatapointingdevicethatallowedeasiermotiont
4、hroughthetextandevenselectionoftextwouldbeveryusefu1・Theintroductionofthemouse,withtheAppleLisacomputerin1983,rea11ystartedthecomputerpublicontheroadtorelyingonthemouseforroutinecomputertasks.Howdoesthemousework?Wehavetostartatthebottom,sothinkupsidedownfornow.Itallstartsw
5、ithmouseball.Asthemouseballinthebottomofthemouserollsoverthemousepad,itpressesagainstandturnstwoshafts.Theshaftsareconnectedtowheelswithseveralsmallholesinthem.Thewheelshaveapairofsmallelectroniclight-emittingdevicescalledlightemittingdiodes(LED)mountedoneitherside.OneLEDs
6、endsalightbeamtotheLEDontheotherside.Asthewheelsspinandaholerotatesby,thelightbeamgetsthroughtotheLEDontheotherside.Butamomentlaterthelightbeamisblockeduntilthenextholeisinplace.TheLEDdetectsachangingpatternoflight,convertsthepatternintoanelectronicsignal,andsendsthesignal
7、tothecomputerthroughwiresinacablethatgoesoutthemousebody.Thiscableisthetailthathelpsgivethemouseitsname.Thecomputerinterpretsthesignaltotel1itwheretopositionthecursoronthecomputerscreen.Sofarwehaveonlydiscussedthebasiccomputermousethatmostofyouprobablyhaveorhaveused.Onepro
8、blemwiththisdesignisthatthemousegetsdirtyasthebal1rollsoverthesurfaceandpicksupthedirt.Ev
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