雅思阅读题.docx
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雅思阅读题
雅思阅读题
Don'twashthosefossils!
StandardmuseumpracticecanwashawayDNA.
1.Washing,brushingandvarnishingfossils—allstandardconservationtreatmentsusedbymanyfossilhuntersandmuseumcuratorsalike—vastlyreducesthechancesofrecoveringancientDNA.
2.Instead,excavatorsshouldbehandlingatleastsomeoftheirbountywithgloves,andfreezingsamplesastheyarefound,dirtandall,concludesapaperintheProceedingsoftheNationalAcademyofSciencestoday.
3.AlthoughmanypalaeontologistsknowanecdotallythatthisisthebestwaytouptheoddsofextractinggoodDNA,Eva-MariaGeigloftheJacquesMonodInstituteinParis,France,andhercolleagueshavenowshownjusthowimportantconservationpracticescanbe.Thisinformation,theysay,needstobehammeredhomeamongthepeoplewhoareactuallyoutinthefielddiggingupbones.
4.Geiglandhercolleagueslookedat3,200-year-oldfossilbonesbelongingtoasingleindividualofanextinctcattlespecies,calledanaurochs.ThefossilsweredugupatasiteinFranceattwodifferenttimes—eitherin1947,andstoredinamuseumcollection,orin2004,andconservedinsterileconditionsat-20ºC.
5.Theteam'sattemptstoextractDNAfromthe1947bonesallfailed.Thenewlyexcavatedfossils,however,allyieldedDNA.
6.Becausetheboneshadbeenburiedforthesameamountoftime,andinthesameconditions,theconservationmethodhadtobetoblamesaysGeigl."AsmuchDNAwasdegradedinthese57yearsasinthe3,200yearsbefore,"shesays.
Washin,washout
7.Becausemanypalaeontologistsbasetheirworkontheshapeoffossilsalone,theirmethodsofconservationarenotdesignedtopreserveDNA,Geiglexplains.
8.Thebiggestproblemishowtheyarecleaned.Fossilsareoftenwashedtogetheron-siteinalargebath,whichcanallowwater—andcontaminantsintheformofcontemporaryDNA—topermeateintotheporousbones."NotonlyistheauthenticDNAgettingwashedout,butcontaminationisgettingwashedin,"saysGeigl.
9.MostancientDNAspecialistsknowthisalready,saysHendrikPoinar,anevolutionarygeneticistatMcMasterUniversityinOntario,Canada.Butthatdoesn'tmeanthatbestpracticehasbecomewidespreadamongthosewhoactuallyfindthefossils.
10.GettingholdoffossilsthathavebeenpreservedwiththeirDNAinmindreliesoncloserelationshipsbetweenlab-basedgeneticistsandtheexcavators,sayspalaeogeneticistSvantePääbooftheMaxPlanckInstituteforEvolutionaryAnthropologyinLeipzig,Germany.Andthatonlyoccursinexceptionalcases,hesays.
11.Pääbo'steam,whichhasbeensequencingNeanderthalDNA,continuallyfacestheseproblems."WhenyouwanttostudyancienthumanandNeanderthalremains,there'sabigissueofcontaminationwithcontemporaryhumanDNA,"hesays.
12.Thisdoesn'tmeanthatallmuseumspecimensarefatallyflawed,notesPääbo.TheNeanderthalfossilsthatwererecentlysequencedinhisownlab,forexample,hadbeenpartofamuseumcollectiontreatedinthetraditionalway.ButPääboiskeentoseesamplesoffossilsfromeverymajorfindpreservedinlinewithGeigl'srecommendations—justincase.
Warmandwet
13.Geiglherselfbelievesthat,withcooperationbetweenbenchandfieldresearchers,preservingfossilsproperlycouldopenupavenuesofdiscoverythathavelongbeenassumedclosed.
14.Muchhumanculturaldevelopmenttookplaceintemperateregions.DNAdoesnotsurvivewellinwarmenvironmentsinthefirstplace,andcanvanishwhenfossilsarewashedandtreated.Forthisreason,Geiglsays,mostancientDNAstudieshavebeendoneonpermafrostsamples,suchasthewoollymammoth,oronremainsshelteredfromtheelementsincoldcaves—includingcavebearandNeanderthalfossils.
15.Betterconservationmethods,andafocusonfreshfossils,couldboostDNAextractionfrommoredelicatespecimens,saysGeigl.Andthatcouldshedmorelightonthestoryofhumanevolution.
(640wordsnature)
Whydidapromisingheartdrugfail?
Doomeddrughighlightscomplicationsofmeddlingwithcholesterol.
1.Thefailureofahigh-profilecholesteroldrughasthrownaspotlightonthecomplicatedmachinerythatregulatescholesterollevels.Butmanyresearchersremainconfidentthatdrugstoboostlevelsof'good'cholesterolarestilloneofthemostpromisingmeanstocombatspirallingheartdisease.
2.DrugcompanyPfizerannouncedon2Decemberthatitwascancellingallclinicaltrialsoftorcetrapib,adrugdesignedtoraiseheart-protectivehigh-densitylipoproteins(HDLs).Inatrialof15000patients,asafetyboardfoundthatmorepeoplediedorsufferedcardiovascularproblemsaftertakingthedrugplusacholesterol-loweringstatinthanthoseinacontrolgroupwhotookthestatinalone.
3.Thenewscameasakickintheteethtomanycardiologistsbecauseearliertestsinanimalsandpeoplesuggesteditwouldlowerratesofcardiovasculardisease."Therehavebeennoredflagstomyknowledge,"saysJohnChapman,aspecialistinlipoproteinsandatherosclerosisattheNationalInstituteforHealthandMedicalResearch(INSERM)inPariswhohasalsostudiedtorcetrapib."Thiscancellationcameasacompleteshock."
4.TorcetrapibisoneofthemostadvancedofanewbreedofdrugsdesignedtoraiselevelsofHDLs,whichferrycholesteroloutofartery-cloggingplaquestotheliverforremovalfromthebody.Specifically,torcetrapibblocksaproteincalledcholesterolestertransferprotein(CETP),whichnormallytransfersthecholesterolfromhigh-densitylipoproteinstolowdensity,plaque-promotingones.Statins,incontrast,mainlyworkbyloweringthe'bad'low-densitylipoproteins.
Underpressure
5.Researchersarenowtryingtoworkoutwhyandhowthedrugbackfired,somethingthatwillnotbecomeclearuntiltheclinicaldetailsarereleasedbyPfizer.Onehintliesinevidencefromearliertrialsthatitslightlyraisesbloodpressureinsomepatients.Itwasthoughtthatthismildproblemwouldbeoffsetbytheheartbenefitsofthedrug.Butitispossiblethatitactuallyprovedfatalinsomepatientswhoalreadysufferedhighbloodpressure.Ifbloodpressureistheexplanation,itwouldactuallybegoodnewsfordrugdevelopersbecauseitsuggeststhattheproblemsarespecifictothiscompound.OtherprototypedrugsthatarebeingdevelopedtoblockCETPworkinaslightlydifferentwayandmightnotsufferthesamedownfall.
6.ButitisalsopossiblethatthewholeideaofblockingCETPisflawed,saysMotiKashyap,whodirectsatherosclerosisresearchattheVAMedicalCenterinLongBeach,California.WhenHDLsexcretecholesterolintheliver,theyactuallyrelyonLDLsforpartofthisprocess.SoinhibitingCETP,whichpreventsthetransferofcholesterolfromHDLtoLDL,mightactuallycauseanabnormalandirreversibleaccumulationofcholesterolinthebody."You'reblockingaphysiologicmechanismtoeliminatecholesterolandeffectivelyconstipatingthepathway,"saysKashyap.
Goingup
7.Mostresearchersremainconfidentthatelevatinghighdensitylipoproteinslevelsbyonemeansoranotherisoneofthebestroutesforhelpingheartdiseasepatients.ButHDLsarecomplexandnotentirelyunderstood.Oneapproveddrug,calledniacin,isknowntobothraiseHDLandreducecardiovascularriskbutalsocausesanunpleasantsensationofheatandtingling.Researchersareexploringwhethertheycanbypassthissideeffectandwhetherniacincanlowerdiseaseriskmorethanstatinsalone.Scientistsarealsoworkingonseveralothermeanstobumpuphigh-densitylipoproteinsby,forexample,introducingsyntheticHDLs."Theonlythingweknowisdeadinthewateristorcetrapib,notthewholeideaofraisingHDL,"saysMichaelMiller,directorofpreventivecardiologyattheUniversityofMarylandMedicalCenter,Baltimore.
(613wordsnature)
Questions1-7
Thispassagehas7paragraphs1-7.
Choosethecorrectheadingforeachparagraphfromthelistofheadingsbelow.
Writethecorrectnumberi-ixinboxes1-7onyouranswersheet.
ListofHeadings
i.Howdoestorcetrapibwork?
ii.Contradictoryresultpriortothecurrenttrial
iii.Onefailuremaypossiblybringaboutfuturesuccess
iv.Thefailuredoesn’tleadtototallossofconfidence
v.Itistherightroutetofollow
vi.Whyit’sstopped
vii.Theymaycombineandtheoreticallyproduceidealresult
viii.What’swrongwiththedrug
ix.Itmightbewrongatthefirstplace
Exampleanswer
Paragraph1iv
1.Paragraph2
2.Paragraph3
3.Paragraph4
4.Paragraph5
5.Paragraph6
6.Paragraph7
Questions7-13
Matchtorcetrapib,HDLs,statinandCETPwiththeirfunctions(Questions8-13)..
WritethecorrectletterA,B,CorDinboxes8-13onyouranswersheet.
NBYoumayuseanylettermorethanonce.
7.Ithasbeenadministeredtoover10,000subjectsinaclinicaltrial.
8.Itcouldhelpridhumanbodyofcholesterol.
9.Researchersareyettofindmoreaboutit.
10.Itwasusedtoreducethelevelofcholesterol.
11.AccordingtoKashyap,itmightleadtounwantedresultifit’sblocked.
12.Itproducedcontradictoryresultsindifferenttrials.
13.ItcouldinhibitLDLs.
Listofchoices
A.Torcetrapic
B.HDLS
C.Statin
D.CETP
TheTriumphofUnreason
A.
Neoclassicaleconomicsisbuiltontheassumptionthathumansarerationalbeingswhohaveaclearideaoftheirbestinterestsandstrivetoextractmaximumbenefit(or“utility”,ineconomist-speak)fromanysituation.Neoclassicaleconomicsassumesthattheprocessofdecision-makingisrational.Butthatcontradictsgrowingevidencethatdecision-makingdrawsontheemotions—evenwhenreasonisclearlyinvolved.
B.
Theroleofemotionsindecisionsmakesperfectsense.Forsitu