2022年大学英语考试模拟卷四20测

2022年大学英语考试模拟卷四（本卷共分为1大题50小题,作答时间为!80分钟,总分100分,60分及格。）单位:姓名: 考号:题号单选题多项选择判断题综合题总分分值得分ー、单项选择题（共50题,每题2分。每题的备选项中,只有一个最符合题意）Questions8to9arebasedonthefollowingnews.Attheendofthenewsitem,youwiIIbegiven10secondstoanswereachquestion.NowIistentothenews.NASAwiIImakealIofthefollowingaccessibleonIineEXCEPT.real-timeweatherforecastingreal-timetrackingofthespaceshuttle3DmapsoftheMars3DmapsoftheEarthWhentheendoftheworIdcomes,we'IIknowwhattobIame.Scientistshavefoundcompe11ingevidencethattheSunhasababybrother,adarkstarwhoseeccentricorbitisresponsibleforperiodicallyshoweringtheEarthwithcometsandmeteorites.Thedarkstar-namedNemesisbyastronomers-isthoughttobeabrowndwarfthatspinsroundtheSuninanorbitsolargeitismeasuredinIightyears,thedistanceIighttravelsinayear,equivaIenttoabout6,000billionmiles.Theresearchsuggeststhat,every26myears,thestar'seccentricorbitbringsitwithinoneIightyearofthesolarsystem.ThereitcauseshavocintheOortCloud,ahugeregionsurroundingthesolarsystemthatcontainsbillionsofbitsofcosmicrabbleleftoverfromtheformationofplanets.Ofthemillionsofrocksitthrowsoutoforbitateachvisit,somehurtleEarthwards,andhaveseveraltimesnearlywipedoutIifeonEarth.AstronomershavelongwonderediftheSunhasasmalIerpartner.Recently,twoindependentgroupsofresearchershavefoundevidenceofone.Onegroup,ledbyJohnMatese,professorofphysicsattheUniversityofLouisianaatLafayette,confirmsthenotionthatitismostIikeIytobeabrowndwarf,astarthatneveraccumuIatedenoughmasstoigniteandwhichhassimplysatinspacesmoIderingforbi11ionsofyears.Matesestudied82cometsfromtheOortCloudandfoundcommoneIementsintheshapeoftheirorbitsthatcouIdonlybeexpIainediftheyhadbeeninfIuencedbythegravitationalpulIofanobjectseveraltimesthesizeofJupiterandexistingabout25,000timesfartherfromtheSunthantheEarth.Matesesaid:”AcompaniontotheSunorbitingatthesedistanceswouldhaveIittIeeffectontheplanets.Butitwouldplayabigroleinthewaycomets'madetheirway'fromtheirbirthplacesintheplanetarydiscouttotheOortCloudandinhowtheycanreturntotheinnersolarsystem.HFurtherresearchwaspubIishedbyRichardMuiler,professorofphysicsattheUniversityofCalifornia,Berkeley,followinganalysesofmoonrocksampIesbroughtbacktoEarthbyApoIIo14.Theabsenceofaprotectiveatmospheremeansthemoonhasbeensubjectedtointensebombardmentinits4.5billion-yearexistence.Muiler'sbreakthroughwastofindawaytodatehowlongagoanyparticlewasmeIted-meaninghecouldbuildupapictureofwhetherthemoongetsaconstantbarrageorsuffersspeIIsofintensebombardment.Hesaid,“TheevidenceclearlyshowsthatthemoonhasgonethroughspeIIsofrelativelyfrequentimpactsandothersofreducedintensity.IbeIieveitisIikeIythatthisisbecausetheOortCloudisbeingdisturbedbyamassivebodythatisthrowingcometsoutofstabIeorbits,asmalIfractionofwhichcouldreachtheEarth.”MuiIerandothersbeIievethatthedarkstarprobablytakesabout26myearstocompIeteanorbitaroundthesun.OtherscientistshavealreadynotedthatmassextinetionsofIifeonEarthseemtooccurinapatternwithgapsequivalenttomultiplesof26m,suggestingsomeregulareventiscausingthecometstocomeEarth'sway.Thebest-knownsucheventwastheonethatwipedoutthedinosaurs65myearsago,butthatwasnottheworst;theplanethassufferedseveralsuchlargemassextinctions.AstronomershavefoundthefirstEarth-sizedpIanetorbitinganotherstar.ThediscoveryraisesthechancesoffindingplanetsthatcouldsupportIifeasweknowit.WhichofthefollowingisNOTafeatureoftheNemesisItcontributestoshoweringofcometsontheearth.ItisasmallerpartneroftheSun.Ithasalargeorbit.ItcontainsbitsofcosmicrubblStratford-on-Avon,aswealIknow,hasonlyoneindustry-WilliamShakespeare-buttherearetwodistinetIyseparateandincreasinglyhostiIebranches.ThereistheRoyalShakespeareCompany(RSC),whichpresentssuperbproductionsoftheplaysattheShakespeareMemorialTheatreontheAvon.Andtherearethetownsf〇IkwholargelyIiveoffthetouristswhocome,nottoseethepIays,buttoIookatAnneHathaway'sCottage,Shakespeare'sbirthplaceandtheothersights.TheworthyresidentsofStratforddoubtthatthetheatreaddsapennytotheirrevenue.TheyfranklydisIiketheRSC'sactors,thosewiththeirlonghairandbeardsandsandalsandnoisiness.It'saildeliciouslyironicwhenyouconsiderthatShakespeare,whoearnstheirIiving,washimselfanactor(withabeard)anddidhisshareofnoise-making. Thetouriststreamsarenotentirelyseparate.ThesightseerswhocomebybusandoftentakeinWarwickCastIeandBlenheimPaIaceonthesidedon'tusuallyseetheplays,andsomeofthemareevensurprisedtofindatheatreinStratford.However,theplaygoersdomanageaIittIesight-seeingalongwiththeirplaygoing.Itistheplaygoers,theRSCcontends,whobringinmuchofthetown'srevenuebecausetheyspendthenight(someofthemfourorfivenights)pouringcashintothehoteIsandrestaurants.ThesightseerscantakeineverythingandgetoutoftownbynightfaII.Thetownsf〇Ikdon'tseeitthisWayandlocalcounciIdoesnotcontributedirectIytothesubsidyoftheRoyaIShakespeareCompany.Stratfordcriespoortraditionally.NeverthelesseveryhotelintownseemstobeaddinganewwingorcocktaiIlounge.HiItonisbuiIdingitsownhotelthere,whichyoumaybesurewiIIbedecoratedwithHamIetHamburgerBars,theLearLounge,theBanquoBanquetingRoom,andSoforth,andwiIIbeveryexpensive.Anyway,thetownsf〇Ikcan'tunderstandwhytheRoyalShakespeareCompanyneedsasubsidy.(Thetheatrehasbrokenattendancerecordsforthreeyearsinarow.Lastyearits1,431seatswere94percentoccupiedaiIyearlongandthisyearthey'IIdobetter.)Thereason,ofcourse,isthatcostshaverocketedandticketpriceshavestayedlow.ItwouldbeashametoraisepricestoomuchbecauseitwoulddriveawaytheyoungpeopIewhoareStratford'smostattractiveclientele.Theycomeentirelyfortheplays,notthesights.TheyalIseemtolookalike(thoughtheycomefromalIover)—lean,pointed,dedicatedfaces,wearingjeansandsandals,eatingtheirbunsandbeddingdownforthenightontheflagstonesoutsidethetheatretobuythe20seatsand80standing-roomticketsheldforthesleepersandsoldtothemwhentheboxofficeopensat10:30a.m.Fromthefirsttwoparagraphs,welearnthat.thetownsfolkdespisetheRSC,sactorsthetwobranchesoftheRSCdonotgetalongwelltheRSCproduceslimitedquantityofplaysthetownsfolkdenytheRSC,scontributiontothetown'srevenueTherearetwosortsofpeopIeintheworld,whowithequaIdegreesofhealth,andwealth,andtheothercomfortsofIife,become,theonehappy,andtileothermiserabIe.Thisarisesverymuchfromthedifferentviewsinwhichtheyconsiderthings,persons,andevents.Inwhateversituationmencanbeplaced,theymayfindconveniencesandinconveniencies;inwhatevercompany,theymayfindpersonsandconversationmoreorlesspleasing;atwhatevertable,theymaymeetwithmeatsordrinksofbetterandworsetaste,dishesbetterorworsedressed;inwhateverclimatetheywiIIfindgoodandbadweather;underwhatevergovernment,theymayfindgoodandbadlaws,andgoodandbadadministrationofthoselaws;ineverypoemorworkofgeniustheymayseefaultsandbeauties;inaImosteveryfaceandeveryperson,theymaydiscoverfinefeaturesandeffects,goodandbadquaIities.Underthesecircumstances,thetwokindsofpeopIeabovementionedfixtheirattention,thosewhoaretobehappy,ontheconveniencesofthings,thepleasantpartsofconversation,theweII-dresseddishes,thegoodnessofthewines,thefineweather,andenjoyalIwithcheerfulness.Thosewhoaretobeunhappy,thinkandspeakonlyofthecontraries.HencetheyarecontinuaIIydiscontentedthemselves,andbytheirremarkssourthepleasuresofsociety,offendpersonallymanypeople,andmakethemseIveseverywheredisagreeable.Ifthisturnofmindwerefoundedinnature,suchunhappypersonswouldbethemoretobepitied.Thetendencytocriticizeandtobedisgustedisperhapstakenuporiginallybyimitation,andisunawaresgrownintoahabit,whichatpresentstrongmayneverthelessbecuredwhenthosewhohaveitareconvineedofitsbadeffectsontheirfelicity.IhopethisIittIeadmonitionmaybeofservicetothem,andputthemonchangingahabit,whichintheexerciseischieflyanactofimaginationyethasseriousconsequencesinIife,asitbringsonrealgrievesandmisfortunes.Formanyareoffended,nobodylovesthissortofpeople,nooneshowsthemmorethanthemostcommonciviIityandrespect,andscarcelythat;andthisfrequentlyputsthemoutofhumor,anddrawsthemintodisputesandcontentions.Iftheyaimatobtainingsomeadvantageinrankorfortune,nobodywishesthemsuccess,orwiIIstirastep,orspeakaword,tofavortheirpretensions.IftheyincurpubIiccensureordisgrace,noonewiIIdefendorexcuse,andmanyjointoaggravatetheirmisconductvandrenderthemcompIeteIyodious.IfthesepeopIewiIInotchangethisbadhabit,andcondescendtobepleasedwithwhatispleasing,withoutfrettingthemselvesandothersaboutthecontraries,itisgoodforotherstoavoidanacquaintancewiththem,whichisaIwaysdisagreeabIe,andsometimesveryinconvenient,especiallywhenonefindsone1sselfentangledintheirquarrels.Anoldphilosophicalfriendofminegrownfromexperience,wasverycautiousinthisparticular,andcarefullyavoidedanyintimacywithsuchpeopIe.Hehad,Iikeotherphilosophers,athermometertoshowhimtheheatoftheweather,andabarometertomarkwhenitwasIikelytoprovegoodorbad;but,therebeingnoinstrumentinventedtodiscover,atfirstsight,thisunpleasingdispositioninaperson.Heforthatpurposemadeuseofhislegs,oneofwhichwasremarkablyhandsome,theother,bysomeaccident,crookedanddeformed.Ifastranger,atthefirstinterview,regardedhisuglylegmorethanhishandsomeone,hedoubtedhim.Ifhespokeofit,tooknonoticeofthehandsomeleg,thatwassufficienttodeterminemyphilosophertohavenofurtheracquaintancewithhim.Everybodyhasnotthistwo-1eggedinstrument,buteveryonewithalittleattention,mayobservesignsofthatcarping,faultfindingdisposition,andtakethesameresolutionofavoidingtheacquaintanceofthoseinfectedwithit.Ithereforeadvisethosecritical,querulous,discontented,unhappypeople,thatiftheywishtoberespectedandbelovedbyothers,andhappyinthemselves,theyshouldIeaveoffIookingattheuglyleg.Accordingtotheauthor,people9sdifferentwaysofconsideringthingsmayinfIuence.theircomfortsoflifetheirmindstheirfeelingstheirhealthandwealth5.HighinasmoothoceanofskyfIoatedadazzling,majesticsun.FragmentsofpowderycIoud,IikesprayfIungfromawavecrest,sprinkledtheradiant,Iake-bIueheaven. ReIaxedonabundIeofhayinacomerofameadowbathedinsunIight,Paullaydreaming.AgentIebreezewasstirringthesurroundinghedges;beesmoved,hummingthoughtfu11y,fromscarIetpoppytopurpIethistIe;adistantlark,invisibleinblueIight,wasfIoodingthevastrealmoftheskywithglorioussong,asthesunwasfIoodingtheearthwithbriIIiance.BeyondthehedgeabrooktinkledoversoftIygIowingpebbles.Butterflieshoveredabovenoddingclover.AnantwasbusilyexploringtheunchartedterritoryofPaul9ssuntannedwrist.Agrasshopperskiddedbrisklyoverhisankle.Andtheblazingsunwassteadilyscorchinghisfairfreckledfacetobrightlobsterred.Neithersun,norgrasshopper,norant,however,wasabletoarousehim.Notevenwhenaflystartedcrawlingoverhisfacedidheopenhiseyes.ForPaulwasathousandmilesaway,inaworldofeternalsnowandice.Acrossthetoweringmountainrange,abittergaIewasscreamingfuriousIyaswithonehandhegrippedaprojectingknobofrockwhilewithhisaxehehackedoutthenextnarrowfootholdintherock.AstheirinfaIIibIeguide,hewasleadinghisgaIIantpartyofclimbersupatreacherous,verticalwalIofrocktowardstheloftypeakabove,hithertounconqueredbyman.Asingleslip,howevertrivial,wouldprobablyresultindeathforalIofthem.Tohisrighthecouldglimpsethefurrowedglaciersweepingtowardsthevalley,buthewasfartooabsorbedinhistasktoappreciatefullythescenearoundoreventobeawareofaviewofalmostunearthlybeauty.Asuddengustofwindnearlytorehimfromtheledgewherehewasperched.Graduallyheraisedhisfoot,testedthenewfoothoIdonthesheerrockwall,transferredhisweight,andsignaledtotheclimbersbeIow.NotuntiIatractorstartedworkinginthenextfielddidhebecomeconsciousofhisfarfromicysurroundings.Hesatup,wipedhisforeheadwithhishandkerchief,gIancedathiswatchandsighedinresignation.Hehadaheadachethroughsleepinginthehotsun,apaininhisshoulderfromcarryinghisrucksack;hislegsfeltstiffandhisfeetached.Withnoenthusiasmwhateverhepulledthebulgingrucksackoverhisshouldersanddrewalarge-scalemapfromhispocket.Atthefarendofthemeadowtwoslatesinthewall,whichatthispointreplacedthehedge,indicatedastiIe,andbeyondhecouldfaintlyseeathinthreadofpathwhichdwindledandfinallydisappearedasitclimbedthesteepslopeofthedown,quiveringintheglareofthesun.ThewholeofNatureseemedtobeluxuriatinginwarmth,sunshineandpeace.Whereverhelooked,leavesontwigs,grassblades,flowerpetals,alIweresparkIinginsunIight.Fifteenmilesoff,overtheridge,acrossabroadvalleyandthenoverahigher,evensteeperrangeofhillslaytheyouthhosteI:supper,company,acooldipintheriver.Withamomentaryintenselongingforice-axe,blizzard,glacierandheroicexploit(noneofwhichwasatalIfamiIiartohim),PauIstrodeoffunwiIIingIytoIessdramaticbutequaIlyheroicachievementinthetropicaIheatofanEngIishsun.AlIofthefollowingfailedtowakePaulupEXCEPTthe.sungrasshopperflytractorQuestion10isbasedonthefollowingnews.Attheendofthenewsitem,youwiIIbegiven10secondstoanswereachquestion.NowIistentothenews.becomethemostglamorousfootballerintheworldbecomethehighestpaidfootballerintheworldhaveabrightercareerfuturehaveabiggerchallengeinhiscareerQuestions6to7arebasedonthefollowingnews.Attheendofthenewsitem,youwiIIbegiven10secondstoanswereachquestion.NowIistentothenews.AccordingtoAnnan,tosoIvetheIraqprobIem,it'snecessaryto.isolateIranfromtheinternationalcommunityimposerestrictionsonIraqieconomytalktoIranandSyriamakeIranandSyriacompromiseStratford-on-Avon,aswea11know,hasonlyoneindustry-WilliamShakespeare—buttherearetwodistinetIyseparateandincreasinglyhostiIebranches.ThereistheRoyalShakespeareCompany(RSC),whichpresentssuperbproductionsoftheplaysattheShakespeareMemoriaITheatreontheAvon.Andtherearethetownsf〇IkwholargelyIiveoffthetouristswhocome,nottoseethepIays,buttoIookatAnneHathaway9sCottage,Shakespeare1sbirthplaceandtheothersights.TheworthyresidentsofStratforddoubtthatthetheatreaddsapennytotheirrevenue.TheyfranklydisIiketheRSC'sactors,thosewiththeirlonghairandbeardsandsandalsandnoisiness.It'saildeliciouslyironicwhenyouconsiderthatShakespeare,whoearnstheirIiving,washimselfanactor(withabeard)anddidhisshareofnoise-making.Thetouriststreamsarenotentirelyseparate.ThesightseerswhocomebybusandoftentakeinWarwickCastleandBlenheimPaIaceonthesidedon'tusuaIlyseetheplays,andsomeofthemareevensurprisedtofindatheatreinStratford.However,theplaygoersdomanageaIittIesight-seeingalongwiththeirplaygoing.Itistheplaygoers,theRSCcontends,whobringinmuchofthetown'srevenuebecausetheyspendthenight(someofthemfourorfivenights)pouringcashintothehoteIsandrestaurants.ThesightseerscantakeineverythingandgetoutoftownbynightfaII.Thetownsf〇Ikdon'tseeitthisWayandlocalcounciIdoesnotcontributedirectlytothesubsidyoftheRoyaIShakespeareCompany.Stratfordcriespoortraditionally.NeverthelesseveryhotelintownseemstobeaddinganewwingorcocktaiIlounge.HiItonisbuiIdingitsownhotelthere,whichyoumaybesurewiIIbedecoratedwithHamIetHamburgerBars,theLearLounge,theBanquoBanquetingRoom,andSoforth,andwiIIbeveryexpensive.Anyway,thetownsf〇Ikcan'tunderstandwhytheRoyalShakespeareCompanyneedsasubsidy.(Thetheatrehasbrokenattendancerecordsforthreeyearsinarow.Lastyearits1,431seatswere94percentoccupiedaiIyearlongandthisyearthey'IIdobetter.)Thereason,ofcourse,isthatcostshaverocketedandticketpriceshavestayedlow.ItwouldbeashametoraisepricestoomuchbecauseitwoulddriveawaytheyoungpeopIewhoareStratford'smostattractiveclientele.Theycomeentirelyfortheplays,notthesights.TheyalIseemtolookalike(thoughtheycomefromalIover)-lean,pointed,dedicatedfaces,wearingjeansandsandals,eatingtheirbunsandbeddingdownforthenightontheflagstonesoutsidethetheatretobuythe20seatsand80standing-roomticketsheldforthesleepersandsoldtothemwhentheboxofficeopensat10:30a.m.WhatcanbeinferredaboutthesightseersandplaygoersThesightseersnevergotoseetheplays.Sightseersandplaygoersoftencomefromdifferentplaces.PlaygoersoftenvisittheWarwickCastle.Playgoersspendmoremoneythansightseers.9.TherearetwosortsofpeopIeintheworId,whowithequaldegreesofhealth,andwealth,andtheothercomfortsofIife,become,theonehappy,andtileothermiserable.Thisarisesverymuchfromthedifferentviewsinwhichtheyconsiderthings,persons,andevents.Inwhateversituationmencanbeplaced,theymayfindconveniencesandinconveniencies;inwhatevercompany,theymayfindpersonsandconversationmoreorlesspleasing;atwhatevertable,theymaymeetwithmeatsordrinksofbetterandworsetaste,dishesbetterorworsedressed;inwhateverclimatetheywiIIfindgoodandbadweather;underwhatevergovernment,theymayfindgoodandbadlaws,andgoodandbadadministrationofthoselaws;ineverypoemorworkofgeniustheymayseefaultsandbeauties;inaImosteveryfaceandeveryperson,theymaydiscoverfinefeaturesandeffects,goodandbadquaIities.Underthesecircumstances,thetwokindsofpeopIeabovementionedfixtheirattention,thosewhoaretobehappy,ontheconveniencesofthings,thepleasantpartsofconversation,theweII-dresseddishes,thegoodnessofthewines,thefineweather,andenjoyalIwithcheerfulness.Thosewhoaretobeunhappy,thinkandspeakonlyofthecontraries.HencetheyarecontinuaIIydiscontentedthemselves,andbytheirremarkssourthepleasuresofsociety,offendpersonallymanypeople,andmakethemseIveseverywheredisagreeable.Ifthisturnofmindwerefoundedinnature,suchunhappypersonswouldbethemoretobepitied.Thetendencytocriticizeandtobedisgustedisperhapstakenuporiginallybyimitation,andisunawaresgrownintoahabit,whichatpresentstrongmayneverthelessbecuredwhenthosewhohaveitareconvineedofitsbadeffectsontheirfelicity.IhopethisIittIeadmonitionmaybeofservicetothem,andputthemonchangingahabitvwhichintheexerciseischieflyanactofimaginationyethasseriousconsequencesinIife,asitbringsonrealgrievesandmisfortunes.Formanyareoffended,nobodylovesthissortofpeople,nooneshowsthemmorethanthemostcommoncivilityandrespect,andscarcelythat;andthisfrequentIyputsthemoutofhumor,anddrawsthemintodisputesandcontentions.Iftheyaimatobtainingsomeadvantageinrankorfortune,nobodywishesthemsuccess,orwiIIstirastep,orspeakaword,tofavortheirpretensions.IftheyincurpubIiccensureordisgrace,noonewiIIdefendorexcuse,andmanyjointoaggravatetheirmisconduct,andrenderthemcompIeteIyodious.IfthesepeopIewiIInotchangethisbadhabit,andcondescendtobepleasedwithwhatispleasing,withoutfrettingthemselvesandothersaboutthecontraries,itisgoodforotherstoavoidanacquaintancewiththem,whichisaIwaysdisagreeabIe,andsometimesveryinconvenient,especiallywhenonefindsone'sselfentangledintheirquarrels.Anoldphilosophicalfriendofminegrownfromexperience,wasverycautiousinthisparticular,andcarefullyavoidedanyintimacywithsuchpeopIe.Hehad,Iikeotherphilosophers,athermometertoshowhimtheheatoftheweather,andabarometertomarkwhenitwasIikelytoprovegoodorbad;but,therebeingnoinstrumentinventedtodiscover,atfirstsight,thisunpIeasingdispositioninaperson.Heforthatpurposemadeuseofhislegs,oneofwhichwasremarkablyhandsome,theother,bysomeaccident,crookedanddeformed.Ifastranger,atthefirstinterview,regardedhisuglylegmorethanhishandsomeone,hedoubtedhim.Ifhespokeofit,tooknonoticeofthehandsomeleg,thatwassufficienttodeterminemyphilosophertohavenofurtheracquaintancewithhim.Everybodyhasnotthistwo-1eggedinstrument,buteveryonewithalittleattention,mayobservesignsofthatcarping,faultfindingdisposition,andtakethesameresolutionofavoidingtheacquaintanceofthoseinfectedwithit.Ithereforeadvisethosecritical,querulous,discontented,unhappypeople,thatiftheywishtoberespectedandbelovedbyothers,andhappyinthemselves,theyshouldIeaveoffIookingattheuglyleg.WhichofthefollowingstatementscanbestsummarizethesecondparagraphA.Oneman*smeatmaybeanotherman'spoison.WheninRome,doasRomansdo.Everyswordhastwoedges.Therecanbealighteningbolt.10.Questions8to9arebasedonthefollowingnews.Attheendofthenewsitem,youwiIIbegiven10secondstoanswereachquestion.NowIistentothenews.HowmuchdidGoogIespendonYouTube$1,800,000,000.$18,000,000.$80,000,000,000.$80,000,000.Whentheendoftheworldcomes,we'11knowwhattobIame.Scientistshavefoundcompe11ingevidencethattheSunhasababybrother,adarkstarwhoseeccentricorbitisresponsibleforperiodicallyshoweringtheEarthwithcometsandmeteorites.Thedarkstar-namedNemesisbyastronomers-isthoughttobeabrowndwarfthatspinsroundtheSuninanorbitsolargeitismeasuredinIightyears,thedistanceIighttravelsinayear,equivaIenttoabout6r000billionmiles.Theresearchsuggeststhat,every26myears,thestar'seccentricorbitbringsitwithinoneIightyearofthesolarsystem.ThereitcauseshavocintheOortCloud,ahugeregionsurroundingthesolarsystemthatcontainsbiIIionsofbitsofcosmicrabbleleftoverfromtheformationofplanets.Ofthemillionsofrocksitthrowsoutoforbitateachvisit,somehurtleEarthwards,andhaveseveraltimesnearlywipedoutIifeonEarth.AstronomershavelongwonderediftheSunhasasmalIerpartner.Recently,twoindependentgroupsofresearchershavefoundevidenceofone.Onegroup,ledbyJohnMatese,professorofphysicsattheUniversityofLouisianaatLafayette,confirmsthenotionthatitismostIikeIytobeabrowndwarf,astarthatneveraccumuIatedenoughmasstoigniteandwhichhassimplysatinspacesmoIderingforbi11ionsofyears.Matesestudied82cometsfromtheOortCloudandfoundcommoneIementsintheshapeoftheirorbitsthatcouIdonlybeexpIainediftheyhadbeeninfIuencedbythegravitationaIpulIofanobjectseveraItimesthesizeofJupiterandexistingabout25,000timesfartherfromtheSunthantheEarth.Matesesaid:"AcompaniontotheSunorbitingatthesedistanceswouldhaveIittIeeffectontheplanets.Butitwouldplayabigroleinthewaycomets'madetheirway'fromtheirbirthplacesintheplanetarydiscouttotheOortCloudandinhowtheycanreturntotheinnersolarsystem.HFurtherresearchwaspubIishedbyRichardMuiler,professorofphysicsattheUniversityofCalifornia,Berkeley,followinganalysesofmoonrocksampIesbroughtbacktoEarthbyApoIIo14.Theabsenceofaprotectiveatmospheremeansthemoonhasbeensubjectedtointensebombardmentinits4.5billion-yearexistence.Muller'sbreakthroughwastofindawaytodatehowlongagoanyparticlewasmeIted-meaninghecouldbuildupapictureofwhetherthemoongetsaconstantbarrageorsuffersspelIsofintensebombardment.Hesaid,"TheevidenceclearlyshowsthatthemoonhasgonethroughspeIIsofrelativelyfrequentimpactsandothersofreducedintensity.IbeIieveitisIikeIythatthisisbecausetheOortCloudisbeingdisturbedbyamassivebodythatisthrowingcometsoutofstabIeorbits,asmaIIfractionofwhichcouldreachtheEarth." MuiIerandothersbeIievethatthedarkstarprobablytakesabout26myearstocompIeteanorbitaroundthesun.OtherscientistshavealreadynotedthatmassextinetionsofIifeonEarthseemtooccurinapatternwithgapsequivalenttomultiplesof26m,suggestingsomeregulareventiscausingthecometstocomeEarth'sway.Thebest-knownsucheventwastheonethatwipedoutthedinosaurs65myearsago,butthatwasnottheworst;theplanethassufferedseveralsuchlargemassextinctions.AstronomershavefoundthefirstEarth-sizedpIanetorbitinganotherstar.ThediscoveryraisesthechancesoffindingplanetsthatcouldsupportIifeasweknowit.Whatdoesthepassageimplya