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1、英语专四阅读理解材料练习附答案Therearetwowaystocreatecolorsinaphotograph・Onemethod,calledadditive,startswiththreebasiccolorsandaddsthemtogethertoproducesomeothercolor・Thesecondmethod,calledsubtractive,startswithwhitelight(amixtureofallcolorsinthespectrum)and,bytakingawaysomeoral
2、lothercolors,leavestheonedesired・Intheadditivemethod,separatecoloredlightscombinetoproducevariousothercolors.Thethreeadditiveprimarycolorsaregreen,redandblue(eachprovidingaboutone瞭hirdofthewavelengthsinthetotalspectrum).Mixedinvaryingproportions,theycanproduceallc
3、olors.Greenandredlightmixtoproduceyellow;redandbluelightmixtoproducemagenta;greenandbluemixtoproducecyan.Whenequalpartsofallthreeoftheseprimary嘖oloredbeamsoflightoverlap,themixtureappearswhitetotheeye・Inthesubtractiveprocesscolorsareproducedwhendye(asinpaintorcolo
4、rphotographicmaterials)absorbssomewavelengthsandsopassesononlypartofthespectTum.Thesubtractiveprimariesarecyan(abluishgreen),magenta(apurplishpink)andyellow;theseadditiveprimariesordyesthatabsorbred,greenandbluewavelengthsrespectively,thussubtractingthemfromwhitel
5、ight.Thesedyecolorsarethecomplementarycolorstothethreeadditiveprimariesofred,green.andblue・Properlycombined,thesubtractiveprimariescanabsorballcolorsoflight,producingblack・But,mixedinvaryingproportions,theytoocanproduceanycolorinthespectrum.Whetheraparticularcolor
6、isobtainedbyaddingcoloredlightstogetherorbysubtractingsomelightfromthetotalspectrum・Theresultlooksthesametotheeye・Theadditiveprocesswasemployedforearlycolorphotography.Butthesubtractivemethod,whilerequiringcomplexchemicaltechniques,hasturnedouttobemorepracticaland
7、isthebasisofallmoderncolorfilms・A.Recentdevelopmentsincameratechnology.B.Howtomakewhitelight・A.Theadditiveandsubtractivemethodsofproducingcolor.D.Thediscoveryofthespectrum・A.Red.E.Cyan.C.Magenta・B.Yellow.A・Yellowandblue・B.Magentaandgreen.C.Blackandwhite・D・Cyanandr
8、ed.A.Subtractivecolorsaremorerealistic.B.Thesubtractiveprocessismoreefficient・C.Additivechemicaltechniquesaretoocomplex・D.Theadditiveprocessisstillbeing
