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TEXTONEMostcellsaretransparent—inotherwords,theyarenotverygoodatreflectingorabsorbinglight.Tolookatthemunderamicroscopethusrequirestrickery.Manyofthesetrickskillthecells,andeventhosethatkeepthemalivelookonlyatslicesthrougheachcell,ratherthanseeingthewholethinginthreedimensions.MichaelFeld,oftheMassachusettsInstituteofTechnology,andhiscolleagues,thinktheycanchangethat.Theyhaveinventedawaytolookatcellsthatarestillalive.Moreover,theycandosointhreedimensions.Theirmethodiscalledtomographicphasemicroscopy,anditisreportedinthisweek'sNatureMethods.Insteadofrelyingonabsorbedorreflectedlight,DrFeld'stechniquecelebratestransparencybylookingatlightthatgetsthroughunaltered.Itdoessobymeasuringapropertycalledtherefractiveindex.Thisindexmeasuresthespeedoflightinamaterial.(Lightzipsalongattheactual“speedoflight”,fasterthanwhichnothingcango,onlywhenitistravellingthroughavacuum.)Thedifferentcomponentsofacell,thoughtransparent,havedifferentrefractiveindices.DrFeldandhisteamthereforesetouttomapwhatthesedifferencesare,withaviewtousingthemtodistinguishbetweencellularcomponents.Tomeasuretherefractiveindicesofdifferentpartsofacelltheyuseatechniquecalledinterferometry,whichinvolvessplittingabeamoflightintwo.Onehalf,knownastheobjectbeam,passesthroughthecell;theotherisdirectedalongadifferentpathandactsasareference.Thelengthofthereferencepathissuchthatifnosampleispresent,thetwodaughterbeamswillbeasperfectlyinphasewhentheymeetastheywerewhentheywereseparated.Thecrestsandthetroughsoftheirwaveswillreinforceeachother,andtheresultwillbebrightness.Themorethatthelightpassingthroughthesampleissloweddown,however,themorethetwobeamswillbeoutofphase.Crestwillfallontrough,andtheresultwillbedarkness.ItisthisphaseshiftthatgivesDrFeld'snewformofmicroscopyitsname.Asinglepairofbeamsdoesnot,however,produceausefulimage.Todothatrequiresscanningtheobjectbeamthroughthetargetaboutahundreddifferentways.Fromtherefractiveindexofeachpathitispossible—withtheapplicationofsomesuitablycrunchycomputingpower—toproduceathree-dimensionalimage.Totesthisidea,DrFeldlookedatcervical-cancercells.Ifyouidentifythiscancerearly,thepatientwillprobablysurvive.Missit,andshewilldie.DrFeldwonderedifthechangesthatoccurduringcancerwouldshowupusinghisnewmethod.Theydid,inapartofthecellcalledthenucleolus.Thisistheplacewherethecomponentsofproteinfactoriesaremade.Sincecancercellsgrowrapidly,andthushaveahighdemandforproteins,itwasalikelyplacetoexpectchanges.DrFeldalsohasplanstousebeamsofdifferentcolours,sinceeachcolourhasaslightlydifferentrefractiveindexinagivenmaterial.Thatwouldprovideextradataforthecomputertochewon,andprobablyresultinbetterpictures.Withenoughpictures,DrFeld'stechniquemaymakebiologyastransparentasthecellsitstudies.1．Tomographicphasemicroscopyisdifferentfromtheothertricksthatlookatcellsinthat_____[A]thelightthatgetsthroughthecellsisunalteredintomographicphasemicroscopy.[B]itdoesnotrequirethetrickerytokillcells.[C]itisnotdependentonabsorbedorreflectedlight.[D]itcouldseeallthecomponentsofthecellsfromthreedimensions.2.WhichoneofthefollowingstatementsisTrueofthespeedoflightinmaterials?[A]Lightrunsthefastestwhenitispassesthroughtransparentmaterialsintherealworld[B]Thespeedoflightcanonlybepreciselymeasuredwhenthelightistravelinginvacuum[C]Thespeedoflightinanymaterialisslowerthantheactual“speedoflight”.[D]Thespeedoflightshiftswhenthelighttravelthroughdifferentcells.3．Theresultofdarknessinthetechniqueofinterferometryimpliesthat_____[A]thereisnolightpassingthroughthesample.[B]therefractiveindexofthesampleisverygreat.[C]thespeedofthelightpassingthroughthesampleisveryslow.[D]thetwodaughterbeamsweakeneachother.4．DrFeld’smethodcouldbeappliedintoidentifyingcancerearlyby_____[A]detectingchangesofrefractiveindicesinthecomponentsofproteinfactories.[B]findingoutthechangesoftherefractiveindicesinsomepartsofthecervical-cancercells.[C]examiningthechangesoftherefractiveindicesinthenucleolus.[D]identifyingthechangesoftherefractiveindicesinpartofthenucleolusofthecancercells.5．Thebesttitleofthepassagescouldbe_____[A]ImageoftheTransparentCells.[B]NewTechniqueofCelebratingTransparency.[C]RefractiveIndicesoftheTransparentCells.[D]NewMethodofDetectingCancerCells.篇章剖析：这篇文章讲述了观察透明活细胞的新方法。第一段讲述过去观察方法的问题；第二段讲述新方法X线断层阶段显微镜方法的大致情况；第三、四、五段讲述该方法具体的情况；第六段讲述Feld博士研究的方法可以探测癌症细胞；第七段讲述Feld博士使用不同颜色光束来得到更好的图像。词汇注释：tomographicadj.X线断层的interferometryn.干涉测量crunchyadj.松脆的cervicaladj.子宫的nucleolusn.核仁难句突破：(1)DrFeldandhisteamthereforesetouttomapwhatthesedifferencesare,withaviewtousingthemtodistinguishbetweencellularcomponents.[主体句式]DrFeldandhisteamsetoutto…,withaviewto…[结构分析]这是一个复合句，what引导的是宾语从句；withaviewto…是句子的状语。[句子译文]Feld博士及其小组因此开始寻找这些不同，希望可以通过不同的折射率来辨析细胞的成分。(2)Tomeasuretherefractiveindicesofdifferentpartsofacelltheyuseatechniquecalledinterferometry,whichinvolvessplittingabeamoflightintwo.[主体句式]Tomeasure…theyuseatechnique…[结构分析]这是一个复合句，which引导的定语从句用来修饰前面的interferometry。To不定式结构是目的状语。[句子译文]为了估测某一细胞不同组成部分的折射率，他们使用了一种将一束光线一分为二的干涉测量方法。题目分析：1．Tomographicphasemicroscopyisdifferentfromtheothertricksthatlookatcellsinthat_____1．X线断层阶