大学英语四级考试及答案模拟题三范文.docx

大学英语四级考试及答案模拟题三范文.docx

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大学英语四级考试及答案模拟题三范文

模拟题三

PartⅠWriting（30minutes）

Directions:

Forthispart,youareallowed30minutestowriteacompositiononthetopicDormitoryLife.Youshouldwriteatleast120wordsfollowingtheoutlinegivenbelowinChinese:

DormitoryLife

1.大学宿舍的集体生活是全新的体验。

2.宿舍生活与在家生活的不同之处。

3.宿舍生活利与弊。

PartIIReadingComprehension（SkimmingandScanning）

Directions:

Inthispart,youwillhave15minutestogooverthepassagequicklyandanswerthequestionsonAnswersheet1.

TestingTimes

Researchersareworkingonwaystoreducetheneedforanimalexperiments,butnewlawsmayincreasethenumberofexperimentsneeded.Thecurrentsituation

Inanidealworld,peoplewouldnotperformexperimentsonanimals.Forthepeople,theyareexpensive.Fortheanimals,theyarestressfulandoftenpainful.

Thatidealworld,sadly,isstillsomewayaway.Peopleneednewdrugsandvaccines.Theywantprotectionfromthetoxicityofchemicals.Thesearchforbasicscientificanswersgoeson.Indeed,theEuropeanCommissionisforgingaheadwithproposalsthatwillincreasethenumberofanimalexperimentscarriedoutintheEuropeanUnion,byrequiringtoxicitytestsoneverychemicalapprovedforusewithintheunion'sbordersinthepast25years.

Already,thecommissionhasidentified140,000chemicalsthathavenotyetbeentested.Itwants30,000ofthesetobeexaminedrightaway,andplanstospendbetween~4billion—8billion（$5billion—10billion）doingso.ThenumberofanimalsusedfortoxicitytestinginEuropewillthus,expertsreckon,quintuple（翻五倍）fromjustoverlmayeartoabout5m,unlesstheyaresavedbysomedramaticadvancesinnon-animaltestingtechnology.Atthemoment,roughly10%ofEuropeananimaltestsareforgeneraltoxicity,35%forbasicresearch,45%fordrugsandvaccines,andtheremaining10%avarietyofusessuchasdiagnosingdiseases.

Animalexperimentationwillthereforebearoundforsometimeyet.Butthesearchforsubstitutescontinues,andlastweekendtheMiddleEuropeanSocietyforAlternativeMethodstoAnimalTestingmetinLinz,Austria,toreviewprogress.

Agoodplacetostartfindingalternativesfortoxicitytestsistheliver--theorganresponsibleforbreakingtoxicchemicalsdownintosafermoleculesthatcanthenbeexcreted.Twofirms,onelargeandonesmall,toldthemeetinghowtheywereusinghumanlivercellsremovedincidentallyduringsurgerytotestvarioussubstancesforlong-termtoxiceffects.

Onewayoutoftheproblem

PrimeCyte,thesmallfirm,growsitscellsinculturesoverafewweeksanddosesthemregularlywiththesubstanceunderinvestigation.Thecharacteristicsofthecellsarecarefullymonitored,tolookforchangesintheirmicroanatomy.

Pfizer,thebigfirm,alsodosesitsculturesregularly,butratherthanstudyingindividualcellsindetail,itcountscellnumbers.Ifthenumberofcellsinaculturechangesafterasampleisadded,thatsuggeststhechemicalinquestionisbadfortheliver.

Inprinciple,thesetechniquescouldbeappliedtoanychemical.Inpractice,drugs（and,inthecaseofPrimeCyte,foodsupplements）aretopofthelist.Butthatmightchangeifthecommissionhasitsway:

those140,000screeningslooklikealucrativemarket,althoughnobodyknowswhetherthenewtestswillbereadyforuseby2009,whenthecommissionproposesthattestingshouldstart.

Othertissues,too,canbetestedindependentlyofanimals.Epithelix,asmallfirminGeneva,hasdevelopedanartificialversionoftheliningofthelungs.AccordingtoHuangSong,oneofEpithelix'sresearchers,thefirm'sculturedcellshavesimilarmicroanatomytothosefoundinnaturallunglinings,andrespondinthesamewaytovariouschemicalmessengers.Dr.Huangsaysthattheycouldbeusedinlong-termtoxicitytestsofairbornechemicalsandcouldalsohelpidentifytreatmentsforlungdiseases.

Theimmunesystemcanbemimickedandtested,too.ProBioGen,acompanybasedinBerlin,isdevelopinganartificialhumanlymphnode（淋巴结）which,itreckons,couldhavepreventedtheneardisastrousconsequencesofadragtrialheldinBritainthreemonthsago,inwhich（despitethedraghavingpassedanimaltests）sixmensufferedmultipleorganfailureandnearlydied.Thedrugthemenweregivenmadetheirimmunesystemshyperactive.Sucharesponsewould,thefirm'sscientistsreckon,naveteenidentifiedbytheirlymphnode,whichismadefromcellsthatprovoketheimmunesystemintoaresponse.ProBioGen'slymphnodecouldthusworkbetterthananimaltesting.Asecondalternative

Anotherwayofcuttingthenumberofanimalexperimentswouldbetochangethewaythatvaccinesaretested,accordingtoCoenraadHendriksenoftheNetherlandsVaccineInstitute.Atthemoment,allbatchesofvaccinearesubjecttothesamebatteryoftests.Dr.Hendriksenarguesthatthisisover-rigorous.Whennewvaccineculturesaremade,belt-and-bracestestsobviouslyneedtobeapplied.Butifabatchofvaccineisderivedfromanexistingculture,hesuggeststhatitneedbetestedonlytomakesureitisidenticaltothebatchfromwhichitisderived.Thatwouldrequirefewertestanimals.

Allthissuggeststhatthoughthereisstillsomewaytogobeforedrugs,vaccinesandothersubstancescanbetestedroutinelyoncellsratherthanliveanimals,usefulprogressisbeingmade.Whatishardertoseeishowtheuseofanimalsmightbebanishedfromfundamentalresearch.Weighingthebalance

Inbasicscientificresearch,wheretheobjectistounderstandhow,say,thebrainworksratherthantodevelopadrugtotreatbraindisease,thewholeanimalisoftennecessarilytheobjectofstudy.Indeed,insomecases,scientificadvancesaremakinganimaltestsmorevaluable,ratherthanless.Geneticmodificationtechniquesmeanthatmiceandratscanberemodelledtomakethemexhibitillnessesthattheywouldnotnormallysufferfrom.Also,genesforhumanproteinscanbeaddedtothem,sothatanimaltestswillmorecloselymimichumanresponses.Thisofferstheopportunitytounderstandhumandiseasesbetter,andtoscreentreatmentsbeforehumantrialsbegin.However,theverycreationofthesemutants（突变异种）countsasananimalexperimentinitsownright,sothenumberofexperimentsisincreasingonceagain.

Whatisbadnewsforrodents,though,couldbegoodnewsforprimates.Apesandmonkeysbelongtothesamegroupofmammalsashumans,andarethusseenasthebestsubjectsforcertainsortsofexperiment.Totheextentthatrodentscanbe"humanised",thenumberofprimateexperimentsmightbereduced.

Somepeople,ofcourse,wouldliketoseethemeliminatedaltogether,regardlessoftheeffectonusefulresearch.OnJune6ththeBritishUnionfortheAbolitionofVivisection,ananimal-rightsgroup,calledfortheuseofprimatesinresearchtobebanned.Forgreatapes,thishasalreadyhappened.Britain,Austria,theNetherlands,NewZealandandSwedenhaveendedexperimentsonchimpanzees,gorillas,bonobosandorang-utans.Experimentsonmonkeys,though,arestillpermitted.Andsomecountrieshavenotbannedexperimentsonapes.InAmerica,forexample,about1,000chimpanzeesayearareusedinresearch.

Thisisadifficultarea.Greatapesareman'sclosestrelatives,havingpartedcompanyfromthehumanfamilytreeonlyafewmillionyearsago.Henceitcanbe（andis）arguedthattheyareindispensableforcertainsortsofresearch.Ontheotherhand,arecentstudybyAndrewKnightandhiscolleaguesatAnimalConsultantsInternational,ananimal-advocacygroup,castsdoubtontheclaimthatapesareusedonlyforworkofvitalimportancetohumanity.Importantpaperstendtogetcitedasreferencesinsubsequentstudies,soMr.Knightlookedintothenumberofcitationsreceivedby749scientificpaperspublishedasaresultofinvasiveexperimentsoncaptivechimpanzees.Halfhadreceivednotasinglecitationuptotenyearsaftertheiroriginalpublication.

Thatisdamning.Animalexperimentsareneededfortheadvanceofmedicalscience,nottomentionpeople's

safety.Butifscientistsaretokeepthesympathyofthepublic,theyneedtodobetterthanthat.

1.Thepassagesummarizesharmfuleffectsofanimalexperiment.However,asanimalexperimentisindispensableinanumberofareas,itmightnotbestoppedorreplacedbyotheralternatives.

2.Animalexperimentsareneededinresearchtofindnewdrugsandvaccines,andtofindwaysofprotectionfromthetoxicityofchemicals.

3.ItispredictedbyexpertsthatthenumberofanimalsusedfortoxicitytestinginEuropewillquintupleduetoaplantohavealargevarietyofchemicaltested.

4.Peoplearetryingtofindalternativestoanimaltesting,andtheystartedwithliver.

5.PrimeCyteandPfizerbegantofindalternativestoanimaltestingbecausetheywereadvocatesofanimalprotection.

6.Itisfoundthattissuesfromliver,lung,andimmunesystemcanallbetestedindependentlyofanimals.

7.Althoughthereismorethanonealternativetoanimalexperiment,thereisstillconcernoverhowtoeliminateanimaltestinginfundamentalresearch.

8.Inbasicscientificresearch,theobjectistounderstandhow,say,thebrainworksratherthantodevelopadrugto______braindisease.

9.Indeed,insomecases,scientificadvancesaremakinganimaltests___________

10.Recently,ananimal-advocacygroupcastsdoubtonthescientists'claimthatapesareusedonlyfor__________

PartIVReadingComprehension（ReadinginDepth）

SectionA

Directions:

Inthissection,thereisapassagewithtenblanks.Youarerequiredtoselectonewordforeachblankfromalistofchoicesgiveninawordbankfollowingthepassage.Readthepassagethroughcarefullybeforemaking

yourchoices.Eachchoiceinthebankisidenti