2024剑桥雅思讲义True_False_NG_Questions_Strategy_Practice.docx

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1、IELTSADVANTAGETrue/False/NGQuestionsStrategyPracticeHowhumanmedicinecouldsavetheTasmaniandevilTransmissiblecancersareincrediblyrareinnature,yethaveariseninTasmaniandevils(atypicallydog-sizedmammalwhichlivesinthewildonlyontheAustralianislandofTasmania)onatleasttwoseparateoccasions.NewresearchfromtheU

2、niversityofCambridgehasidentifiedkeyanti-cancerdrugswhichcouldbetrialledasatreatmentforthesediseases,whicharethreateningTasmaniandevilswithextinction.TheresearchalsofoundthatthetwoTasmaniandeviltransmissiblecancersareverysimilartoeachother,andlikelybotharoseduetosusceptibilitiesinherenttothedevilsth

3、emselves.Tasmaniandevilsareconsideredendangeredduetodevilfacialtumour1(DFT1),acancerthatispassedbetweenanimalsthroughthetransferoflivingcancercellswhentheanimalsbiteeachother.DFT1causesgrotesqueanddisfiguringfacialtumourswhichusuallyMilaffectedindividuals.TheDFT1cancerfirstaroseinasingleindividualde

4、vilseveraldecadesago,butratherthandyingtogetherwiththisdevil,thecancersurvivedby4metastasising,intodifferentdevils.Therefore,theDNAofthedevils,tumourcellsisnottheirownDNA,butratherbelongstotheindividualdevilthatfirstgaverisetoDFT1allthoseyearsago.Remarkably,DFT1cellscanescapethedevils*immunesystemsd

5、espitebeinginessenceaforeignbody.TheDFT1cancerwasfirstobservedinnorth-eastTasmaniain1996,buthassubsequentlyspreadwidelythroughouttheisland,causingsignificantdeclinesindevilpopulations.In2014,routinediagnosticscreeningrevealedasecondtransmissiblecancerinTasmaniandevils,devilfacialtumour2(DFT2),whichc

6、ausesfacialtumoursindistinguishabletothenakedeyefromthosecausedbyDFT1,andwhichisprobablyalsospreadbybiting.However,analysisshowedthatthetwotypesofcancerdifferatabiologicallevel,andwhereasDFT1firstarosefromthecellsofafemaledevil,DFT2appearstohavefirstarisenfromamaleanimal.Fornow,DFT2appearstobeconfin

7、edtoapeninsulainTasmania,ssouth-east.uThediscoveryofasecondtransmissiblecancerinTasmaniandevilswasahugesurprise,saysDrElizabethMurchisonfromtheDepartmentofVeterinaryMedicineattheUniversityofCambridge.uOtherthanthesetwocancers,weknowofonlyoneothernaturallyoccurringtransmissiblecancerinmammals-thecani

8、netransmissiblevenerealtumourindogs,whichfirstemergedseveralthousandyearsago.Note:ThisisnotarealIELTStest.Thispracticetestistogiveyouanopportunitytopractiseimplementingthestrategiesfromthecourse.Itdoesnotreflectthescores,timeneededorlevelofdifficultyofarealIELTStest.IELTSADVANTAGETrue/False/NGQuesti

9、onsStrategyPracticeInfact,outsideofmammals,onlyfivetransmissiblecancershavebeenobserved,allofwhichcauseIeukaemia-Iikediseasesinclamsandothershellfish.“Thescarcityoftransmissiblecancerssuggeststhatsuchdiseasesemergerarely,sheadds.Before1996,noonehadobservedtheminTasmaniandevils,sofindingtwotransmissi

10、blecancersinTasmaniandevilsinjusteighteenyearswasverysurprising?Inordertoseewhetherthedeviltransmissiblecancersarecausedbyexternalfactorsorwhethertheanimalswerejustparticularlysusceptibletodevelopingthesecancers,aresearchteamledbyDrMurchisonanalysedthegeneticprofilesofDFT1andDFT2tumourstakenfromanum

11、berofTasmaniandevils.Theteamfoundstrikingsimilaritiesintissues-of-origin,genetics,howthecancercellsmutate,andpossibledrugtargets.Thisimpliesthatthetwotumoursbelongtothesamecancertypeandaroseviasimilarmechanisms.Theteamstudiedthegeneticandphysicalfeaturesofthetumours,andcomparedthetwolineageswitheach

12、otherandwithhumancancers.Indoingso,theyidentifiedanimportantroleinthetumoursforparticulartypesofmoleculesknownasreceptortyrosinekinases(RTKs)insustaininggrowthandsurvivalofDFTcancers.Importantly,drugstargetingRTKshavealreadybeendevelopedforhumancancer,andtheresearchersshowedthatthesedrugsefficiently

13、stoppedthegrowthofdevilcancercellsgrowinginthelab.ThisleadstohopethatitmaybepossibletousethesedrugstohelpTasmaniandevils.WhyTasmaniandevilsshouldbeparticularlysusceptibletotheemergenceofDFTsisnotclear.However,devilsbiteeachotherfrequentlyaroundthefacialarea,oftencausingsignificanttissueinjury.Givent

14、heimportantroleforRTKmoleculesinwoundhealing,theresearchersspeculatethatDFTcancersmayarisefromerrorsinthemaintenanceofproliferativecellsinvolvedintissuerepairafterinjury.Whenfighting,Tasmaniandevilsoftenbitetheiropponentsface,whichmaypredisposetheseanimalstotheemergenceofthisparticulartypeofcancervi

15、atissueinjury,saysfirstauthorofthestudy,MaximilianStammnitz.uAsbitingoccursontheface,thiswouldsimultaneouslyprovidearouteofcelltransmission.,TheresearcherssayitisalsopossiblethathumanactivitiesmayhaveindirectlyincreasedtheriskoftheemergenceorspreadoftransmissibledevilfacialtumoursNote:Thisisnotareal

16、IELTStest.Thispracticetestistogiveyouanopportunitytopractiseimplementingthestrategiesfromthecourse.Itdoesnotreflectthescores,timeneededorlevelofdifficultyofarealIELTStest.IELTSADVANTAGETrue/False/NGQuestionsStrategyPractice(DFTs)inrecentyears.Forinstance,itispossiblethatsomemodernlandusepracticesmayhaveprovidedfavourableconditionsfordevils,leadingtoanincreaseinlocalpopulationdensitiesofdevils,andtogreatercompetition,interactionsand