陕西省渭南市韩城市2025届高三第一次模拟考试英语试卷含解析

陕西省渭南市韩城市2025届高三第一次模拟考试英语试卷请考生注意：1．请用2B铅笔将选择题答案涂填在答题纸相应位置上，请用0．5毫米及以上黑色字迹的钢笔或签字笔将主观题的答案写在答题纸相应的答题区内。写在试题卷、草稿纸上均无效。2．答题前，认真阅读答题纸上的《注意事项》，按规定答题。第一部分（共20小题，每小题1.5分，满分30分）1．—Onlythosewhohavealotincommoncangetalongwell.—_________.Oppositessometimesdoattract.A．Ihopenot B．IthinksoC．Iappreciatethat D．Ibegtodiffer2．Theworld’sattention________China’sBeltandRoadInitiative，asithasgreatinfluenceontheworld’seconomy.A．istofixon B．wasfixedonC．hasfixedon D．isbeingfixedon3．Don'tyouthink_______ofgreatimportancethatweshouldkeepfitbytakingexerciseregularly?A．this B．that C．which D．it4．TherewasneveranytimeforKatetofeellonely,________shewasanonlychild.A．eversince B．nowthatC．eventhough D．asthough5．Itwaswarmandnicethatevening.Istayedawakeuntileleveninordertohaveagoodlookatthemoonbymyself.A．onaverageB．onpurposeC．onbusinessD．ontime6．Thiskindofgelpenwhich______smoothlyisquitepopularwithstudents.A．iswrittenB．iswritingC．wroteD．writes7．----CouldIaskyouaprivatequestion?----Sure,A．pardonmeB．goaheadC．goodideaD．forgetit8．—Bettywasfeelingprettyblueforawhile,butshe’sbetternow.—_______.A．Oh,that’skindofyou B．CongratulationsC．Oh,I’mgladtohearthat D．It’smypleasure9．---Areyoufreenow?Ihavesomethinginterestingtotellyou.---OK,youmakeitshortIwillhavetoworkonthistermpaperduetomorrow.A．nowthatB．assoonasC．everytimeD．aslongas10．PremierLiKeqiangofficially______theplantodeveloptheBayAreainhisgovernmentworkreportdeliveredatthestartoftheNationalPeople’sCongresssessioninMarch.A．laidoutB．laidoffC．laiddownD．laidup11．Luciaimpressedherpeerstudentswithhermusicaltalent,aswellasseveralforeignlanguages______.A．onherown B．underhercontrol C．inhercharge D．athercommand12．Thetwobirds_________eachotherinshapeandcolor.Inotherwords,they_________eachotherinshapeandcolor.A．differ,aredifferentfrom B．differfrom,aredifferenttoC．resemble,aresimilarto D．resemble,aresimilarwith13．Undergoodtreatment,manypatientsarebeginningto________andwillsoonrecover.A．turnupB．catchupC．pickupD．showup14．Those

havesixormoreclosefriendsaredescribedas"veryhappy".A．whose B．whoC．which D．when15．Hewaselected______presidentofthecompany,and_____newscame,infact,as______surprise.A．a;the;X B．X;the;a C．a;X;the D．the;the;a16．—Dad,youshouldhavetakenmetothefootballmatchthismorning.—Ihadintendedto,butIcouldn’tspareanytime,I_____areport.A．hadwrittenB．wroteC．waswritingD．wouldwrite17．—Shallweputofftheexperimenttillnextweek?—______,Idon’tthinkourteacherwillbehappywithit.A．Nevermind B．Sure,goaheadC．Yes,betternot D．I’drathernot18．—Iwanttolearntennis.Wouldyouliketohelpme?—.Butlearningtennisisnowalkinthepark.A．NokiddingB．NowonderC．NoproblemD．Noway19．—WillittakemelongtogettotheSunshineHotel?—No,it______takeyoulong.It’snottherushhournow.A．shouldn’t B．shan’tC．mustn’t D．needn’t20．Smelltheflowersbeforeyougotosleep,andyoumayjust________sweetdreams.A．keepupwith B．putupwith C．endupwith D．catchupwith第二部分阅读理解（满分40分）阅读下列短文，从每题所给的A、B、C、D四个选项中，选出最佳选项。21．（6分）Newsanchors(主播)musthavebeenreluctanttoreadoutthefollowingnews:XinXiaomengbeganworkingastheworld’sfirstfemaleartificial(人工的)intelligencenewsanchoratXinhuaNewsAgencyonSunday,threemonthsafteramalerobotjoinedtheprofession.Unlikepreviousnewsrobotsthough,Xindoesnotreadnewslikeacoldmachine;shereadsitalmostlikeahumanbeing.Themusclesonherfacestretchandrelax-andherreactionschange-asshecontinuesreading.That’swhymanynewsanchorswereworried:WillAIreplaceusinthenearfuture?Tofindtheanswer,wehavetoanalysethetechnologiesthatsupportXinatherjob.ThreekeytechnologiesareusedtosupportXin.First,samplesofhumanvoicesarecollectedandsynthesized(合成).Thisisfollowedbythecollectionandsynthesisofhumanmusclemovementsamples.AndthirdthevoicesandmovementsaremarriedinawaythatwhentheAlnewsanchorreads,themicro-electricmotorsbehindherfacemovetomakeherexpressionsseemmorehuman.Yetweneedathoroughknowledgeofdeepleaningtechnologytomakearobotimitateaperson’svoice.Thedeveloperneedstocollecttensofthousandsofpiecesofpronunciations,inputthemIntothemachineandmatchthemwiththetextortheAltoleanandread.Theprocessforimitatingfacialmovementsissimilar.Thedeveloperhastoanalysethemovementsofthe53musclesinthehumanface,makeamodelsetfromthecollecteddatafortheAInewsanchortolean,andimitatethemovementsoffacialmusclesviaprogramsBoththetechnologiesusedtomakeXin’sperformanceimpressivearemature.Therealdifficultyliesinthethird-thetechnologytomatchthepronunciationswithfacialmovementssothatXinexpressionsvaryaccordingtothecontentofthenewsreport.Infact,Xinsexpressionsdon'talwayschangeaccordingtothecontent.Asaresult,herexpressionslookanythingbuthuman.Actually.AIisstillnomatchforhumanqualities.1、Whatdoestheunderlinedword"reluctant"inthefirstparagraphmean?A．Delighted. B．Unwilling. C．Confused. D．Optimistic.2、Whatcanweinferaboutpreviousnewsrobots?A．Theyreadnewswithoutexpressions. B．TheylookedlikeahumanbeingC．Theycouldinterviewsportsstars D．Theycouldinteractwithaudience.3、Whatdoweknowaboutthethirdtechnology?A．ThistechnologyisveryperfectsofarB．ThistechnologyisquitepopularnowC．ThistechnologyremainsatthetheoreticalstageD．Thistechnologyisfarfrommature.4、Fromthelastparagraph,wecandrawaconclusionthat____.A．humannewsanchorsshouldlearnfromATanchorstosavetheirjobsB．AlanchorsperformmuchbetterthanhumannewsanchorsatpresentC．Alnewsanchorswon'treplacehumannewsanchorsinthenearfutureD．XinXiaomengsexpressionsvarysonaturallythattheyaretruetolife22．（8分）Supposeyoubecomealeaderinanorganization.It’sverylikelythatyou’llwanttohavevolunteerstohelpwiththeorganization’sactivities.Todoso,itshouldhelptounderstandwhypeopleundertakevolunteerworkandwhatkeepstheirinterestinthework.Let’sbeginwiththequestionofwhypeoplevolunteer.Researchershaveidentifiedseveralfactorsthatmotivatepeopletogetinvolved.Forexample,peoplevolunteertoexpresspersonalvaluesrelatedtounselfishness,toexpandtheirrangeofexperiences,andtostrengthensocialrelationships.Ifvolunteerpositionsdonotmeettheseneeds,peoplemaynotwishtoparticipate.Toselectvolunteers,youmayneedtounderstandthemotivationsofthepeopleyouwishtoattract.Peoplealsovolunteerbecausetheyarerequiredtodoso.Toincreaselevelsofcommunityservice,someschoolshavelaunchedcompulsoryvolunteerprograms.Unfortunately,theseprogramscanshiftpeople’swishofparticipationfromaninternalfactor(e.g.“Ivolunteerbecauseit’simportanttome”)toanexternalfactor(e.g.“IvolunteerbecauseI’mrequiredtodoso”).Whenthathappens,peoplebecomelesslikelytovolunteerinthefuture.Peoplemustbesensitivetothispossibilitywhentheymakevolunteeractivitiesamust.Oncepeoplebegintovolunteer,whatleadsthemtoremainintheirpositionsovertime?Toanswerthisquestion,researchershaveconductedfollow-upstudiesinwhichtheytrackvolunteersovertime.Forinstance,onestudyfollowed238volunteersinFloridaoverayear.Oneofthemostimportantfactorsthatinfluencedtheirsatisfactionasvolunteerswastheamountofsufferingtheyexperiencedintheirvolunteerpositions.Althoughthisresultmaynotsurpriseyou,itleadstoimportantpracticaladvice.Theresearchersnotethatattentionshouldbegivento“trainingmethodsthatwouldpreparevolunteersfortroublesomesituationsorprovidethemwithstrategiesforcopingwiththeproblemtheydoexperience”.Anotherstudyof302volunteersathospitalsinChicagofocusedonindividualdifferencesinthedegreetowhichpeopleview“volunteer”asanimportantsocialrole.Itwasassumedthatthosepeopleforwhomtheroleofvolunteerwasmostpartoftheirpersonalidentitywouldalsobemostlikelytocontinuevolunteerwork.Participantsindicatedthedegreetowhichthesocialrolematteredbyrespondingtostatementssuchas“VolunteeringinHospitalisanimportantpartofwhoIam.”Consistentwiththeresearchers’expectations,theyfoundapositivecorrelation(正相关)betweenthestrengthofroleidentityandthelengthoftimepeoplecontinuedtovolunteer.Theseresults,onceagain,leadtoconcreteadvice:“Onceanindividualbeginsvolunteering,continuedeffortsmightfocusondevelopingavolunteerroleidentity....ItemslikeT-shirtsthatallowvolunteerstoberecognizedpubliclyfortheircontributionscanhelpstrengthenroleidentity”.1、Peoplevolunteermainlyoutof__________.A．academicrequirements B．socialexpectationsC．financialrewards D．internalneeds2、WhatcanwelearnfromtheFloridastudy?A．Follow-upstudiesshouldlastforoneyear. B．Volunteersshouldgetmentallyprepared.C．Strategytrainingisamustinresearch. D．Volunteersareprovidedwithconcreteadvice.3、Whatismostlikelytomotivatevolunteerstocontinuetheirwork?A．Individualdifferencesinroleidentity. B．PubliclyidentifiablevolunteerT-shirts.C．Roleidentityasavolunteer. D．Practicaladvicefromresearchers.4、Whatisthebesttitleofthepassage?A．HowtoGetPeopletoVolunteer B．HowtoStudyVolunteerBehaviorsC．HowtoKeepVolunteers’Interest D．HowtoOrganizeVolunteerActivities23．（8分）Overahundredyearsagoin1911,somethingstrangewasfoundintheglaciersofAntarctica.GrilffithTaylor—anAustraliangeologist,haddiscoveredabloodredsteampouringoutoftheicecascades（瀑布）ofTalorGlacier!PopularlyknownastheBloodFalls,scientistshadnotbeenabletofindthereasonbehindthebloodredliquidflowingthroughtheice---untilrecently.ThemysteryoftheBloodFallshadfinallybeensolved.Whenthesefallswerefirstdiscovered,scientistshadbelievedthattheredcolourcamefromalargeamountofredalgae（海藻）concentratedinthewater.Redalgaecontainapigment（色素）whichreflectsredlight,makingthealgaeappearred.Thistheorymadesense,untilitwaslaterfoundthatalgaedonotplayapartintheredcoloroftheflowingliquidatall.WhatreallycausesTalorGlacier’swatersappearbloodred,isthepresenceofironoxideintheliquid.Thewatersofthebloodfallsarerichinsaltandironcontent,andwhenthiswatercomesincontactwiththeair,itturnsred—justlikerust!Thewaterinthesefallsisoftenreferredtoas“brine”byscientistsbecauseofthehighsaltcontentinthewater.Thisreasoningbehindtheredcolorsofthefallswasfoundbackin2003.However,theentiremysteryhadnotyetbeensolved.Howisitthen,thattheBloodFallsarenotfrozen?ResearchersattheUniversityofColoradoandUniversityofAlaskafoundthatinsidetheglacier,therewasanetworkofchannelsandreservoirsthatmovethewateraround.Saltwaterhasalowerfreezingtemperature.Inaddition,whenanysubstanceundergoesachangeinstate,itgivesoffheat.Therefore,thebrineactuallywarmitselfupwhileit’sfreezing!Howthisworks,isthatwhenthebrineisflowingthroughtheTalorGlacier,someofitdoesfreeze.Asaresultofchangingstatefromliquidtoice,thebrinegivesoffheat.Thisheatisenoughtokeeptherestoftherestofthebrineinliquidform,whichiswhyitflowsoutoftheglacier.Incrediblenewchemistryfactsfound,anymysterysolved!1、Accordingtothetext,theredalgaetheorywasonceconsidered________.A．ridiculousB．reasonableC．impracticalD．complex2、WhydoestheBloodFallslookredincolour?A．Becausethereistoomuchsaltandironinitswater.B．Becauseitsliquidisrichinredalgae.C．BecausethefollowingliquidreflectsandsunlightD．BecausetheairisthinandrareinAntarctica.3、WhatisthemainreasonfortheBloodFall’snotfreezing?A．Thewatercontinuedflowingconstantly.B．Thereistoomuchsaltinthewater.C．ThebrinegivesoffheatwhilefreezingD．Temperaturesaren’thighenoughforflowingwater.4、Whatisthepassagemainlyabout?A．Thediscoveryofthebloodglacier.B．ThebirthoftheTalorGlacier.C．TheflowingredwaterinAntarctica.D．ThemysteryoftheBloodFalls.24．（8分）‘Turtletime!,loudlycalledoutbyoneofmynewly-foundfriends,meantthebeginningofeitheramorningorafternoonshiftatTurtleCampinNusaPenida,Indonesia.Uponarrivalattheprojecteachday,wewouldlookeagerlyforournamesonthewhiteboardtoseewhichtaskwewouldbeundertaking.Woulditbethehighlydesirable‘turtlefeeding’,theprettyfun‘tankcleaning’,theexciting‘medicineadministering’orthelessappealing‘fishcutting’?FineintheorybutnotwheneveryflyinIndonesiadecidestocrowdontothesedeadfishwhileyou’recutting!Lifeattheturtleprojectwasfunbecausetwiceadaywegottohangoutwithseaturtles.By‘hangout’,Iobviouslymeant‘work’,aswewereonshift,butitcertainlydidn’tfeellikework.Anotherfunthingwasgettingtoknowtheothervolunteers!Withvolunteersfromallovertheworld,itwasjustcommontohearFinnishbeingspoken,AustralianslangmixedwithFrenchexpressionsandSwedesmakingplanstovisitnewly-foundfriendsintheUSA．Ofcourse,notallthetimeatTurtleCampwasconsumedbyvolunteering.ScheduledactivitiesincludedatriptoCrystalBay,abeautifulparadiseforswimmingandsunbathing,anawesomebeachbonfirecompletewithabeautifulsunsetaswellasourlocalcoworkersshowingofftheirguitarplayingandsingingskills.OurtimeatTurtleCampwascappedoffbysettingfreetwoofourturtlesintotheseatobegintheirjourneyasindependentturtles!Hopefully,theloveandcareprovidedattheturtleprojectwouldensurethattheseturtleshadagreaterchanceofsurvivalinthebig,wideandscaryocean.1、WhichtaskislessfuntothevolunteersatTurtleCamp?A．Turtlefeeding. B．Tankcleaning.C．MedicineAdministering. D．FishCutting.2、Whatdoestheunderlinedsentenceimply?A．Thevolunteeringwasachallenge.B．Thetimeatthecampwasdifficult.C．Theworkattheprojectwasadelight.D．Communicationwastime-consuming.3、Whensettingfreethetwoturtles,thevolunteersfeltasenseof_________.A．achievement B．belongingC．loss D．independence25．（10分）Everycountrymayhavetoconsiderwhat,ifanything,todoabout“globalwarming”.Weshouldunderstandthattheoft-repeatedclaimthatnearlyallscientistsdemandthatsomethingdramaticbedonetostopglobalwarmingisnottrue.Perhapsthemostinconvenientfactisthelackofglobalwarmingforwellover10yearsnow.Thisisknowntothewarmingestablishment,asonecanseefromthe2009“Climategate”emailofclimatescientistKevinTrenberth:“Thefactisthatwecan’taccountforthelackofwarmingatthemomentanditisanironythatwecan’t.”Butthewarmingisonlymissingifonebelievescomputermodelswhereso-calledfeedbackinvolvingwatervaporandcloudsgreatlyamplifiesthesmalleffectofCO2.ThefactisthatCO2isnotapollutantanditisakeycomponentofthebiosphere(生物圈)’slifecycle.PlantsgetbettergrowthwithmoreofitandpartoftheincreaseofagriculturalyieldsinthepastcenturycertainlycamefromadditionalCO2intheatmosphere.Althoughthenumberofthescientistswhoarepubliclyopposedtotheclaimisgrowing,manyyoungscientistssecretlysaythatwhiletheyalsohaveseriousdoubtsabouttheglobal-warmingmessage,theyareafraidtospeakupforfearofnotbeingpromotedorworse.Whyistheresomuchpassionaboutglobalwarming?Thereareseveralreasons,butagoodplacetostartistheoldquestion“Cuibono?”,orthemodernupdate,“Followthemoney”.Alarmism(危言耸听)overclimateisofgreatbenefittomany,providinggovernmentfundingforacademicresearch,andthusthosepeoplewhobenefitfromthisfiercelydefendedtheirdogma(信条)andtheprivilegesitbroughtthem.Everycountryshouldsupportrational(合理的)measurestoprotectandimproveourenvironment,butitmakesnosenseatalltobackexpensiveprogramsthatturnawayresourcesfromrealneedsandarebasedonalarmingbutshakyclaimsof“incontrovertible”evidence.1、Whatcanweinferabouttheauthor’sopiniononglobalwarming?A．Globalwarminghasn’thappenedinthelatest10years.B．Globalwarminghasbecomeanurgentproblemtheseyears.C．Globalwarminghasworsenedalittlebitintherecentyears.D．Globalwarminghasneverhappenedsincemeasuresweretaken.2、WhichofthefollowingstatementsaboutCO2doesthewriterprobablyagreewith?A．CO2greatlyaffectstheglobalwarming.B．CO2makescropsmoreproductive.C．CO2involveswatervaporandclouds.D．CO2isthemostimportantpartofthebiosphere.3、Whyistheresomuchpassionforglobalwarming?A．Becausetisagoodchanceforyoungscientiststobepromoted.B．Becausethescientistswanttohaveaninsightintotheproblem.C．Becausethegovernmentvaluestheproblemandtriestosolveit.D．Becausesomepeoplecangreatlybenefitfromtheresearchaboutit.4、What’sthewriter’sattitudetowardtheprogramstoprotectandimproveourenvironment?A．Tosupportalltheprogramsaslongastheyarebeneficial.B．Tosupportcheapprogramsinsteadofexpensiveones.C．Tosupporttheprogramsthatarenecessaryandreliable.D．Tosupportthoseprogramsthatuselessmoneyandresources.第三部分语言知识运用（共两节）第一节（每小题1.5分，满分30分）阅读下面短文，从短文后各题所给的A、B、C和D四个选项中，选出可以填入空白处的最佳选项．26．（30分）IlostmysightwhenIwasfouryearsoldbyfallingoffacarandlandingonmyhead.NowIamthirty-two.Icanvaguelyrememberthebrightnessof__36____andwhatcolorredis.Itwouldbe___37____toseeagain,buta(n)__38____candostrangethingstopeople.Idon’tmeanIwould__39___togowithoutmyeyes.IsimplymeanthatthelossofthemmademeappreciatemorewhatIhad_40_____.Myparentsandmyteacherssawsomethinginme-----a__41____tolive----whichIdidn’tsee,andtheymademewanttofightinoutwith_42____.The__43___lessonIhadtolearnwastobelieveinmyself.Iamnottalkingaboutsimplythekindof__44____thathelpsmedownsounfamiliarstaircasealone.I__45___somethingbiggerthanthat:aconfidencethatIam,despitebeing__46____,areal,positiveperson;thatthereisaspecialplacewhereIcanmakemyselffit.Ittookmeyearstodiscoverandstrengthenthisconfidence.Ithadtostartwiththeeasyandsimplethings.__47____amangavemeanindoorbaseball.IthoughthewaslaughingatmeandIwas__48____.“Ican’tusethis,”Isaid.“Takewithyou,”heurgedme,“androllitaround.”Thewords__49___inmyhead.“Rollitaround!”ByrollingtheballIcould_50_____whereitwent.ThisgavemeanideahowtoachieveagoalIhadthought_51____beforeplayingbaseball.AtPhiladelphia’sOverbrookSchoolfortheBlindI_52___asuccessfulvariationofbaseball.Wecalleditgroundball.Ihavesetaheadofmeaseriesofgoalsandthentriedtoreachthem,oneatatime.Ihadtobeclearaboutmy_53____.ItwasnogoodcryingforsomethingthatIknewatthestartwas__54___outofreachbecausethatonlyinvitedbitternessoffailure.Iwouldfailsomethinganyway,__55___ontheaverageImadeprogress.1、A．sky B．cloud C．sunshine D．mist2、A．helpful B．wonderful C．hopeful D．successful3、A．disaster B．environment C．incident D．wonder4、A．manage B．try C．want D．prefer5、A．lost B．left C．used D．cared6、A．purpose B．potential C．pressure D．preparation7、A．energy B．happiness C．luck D．blindness8、A．hardest B．dullest C．simplest D．easiest9、A．self-respect B．self-control C．self-confidence D．self-defence10、A．think B．consider C．guess D．mean11、A．imperfect B．perfect C．unfair D．fair12、A．Later B．Soon C．Once D．Then13、A．worried B．encouraged C．shocked D．hurt14、A．stuck B．impressed C．occupied D．held15、A．see B．hear C．notice D．observe16、A．important B．unimportant C．possible D．impossible17、A．invented B．discovered C．instructed D．directed18、A．experience B．advantages C．knowledge D．limitation19、A．hardly B．wildly C．highly D．deeply20、A．so B．for C．but D．and第二节（每小题1.5分，满分15分）阅读下面材料，在空白处填入1个适当的单词或括号内单词的正确形式。27．（15分）语法填空Dinosaurslivedontheearthtensofmillionsofyearsago,longbeforehumanbeingcameintobeing.Unfortunately(不幸地),theydiedoutbecauseofan__1．__(expect)incident.Butwildlifetodaydisappearsorisindangerjust_2．__humansdoharmtoit.Forexample,tigersarehuntedforfurtomakecarpets,sothattheyonlyliveinsecurereserves;grassland__3．__(destroy)withoutmercy,sothatduststormscomeintobeingaffectingdistantcities.Lastyear,scientistssawsomemonkeysrubbingthemselveswithacertainkindofinsects__4．_(prevent)themselvesfrombeingbittenbymosquitoes.Accordingtotheresultofthestudy,theyfoundthattheinsectcontains__5．__powerfuldrug.Asaresult,localfarmerswereemployedtocatchtheinsects,__6．_ledtotheirdisappearancefromthewholezone.Whentoldthatitwasalosstohumans,thefarmersburstintolaughterandresponded,“Ourreallossisour__7．_(decrease)income.”Therefore,wehumanbeingsshouldappreciatethenaturalbalance(平衡)andpay__8．_(much)attentiontotheimportanceofwildlife__9．__(protect)thanbefore.Notuntilwesucceedinlettingwildlifelive__10．__(peace),canwesmileinrelief.第四部分写作（共两节）第一节短文改错（满分10分）28．（10分）假定英语课上老师要求同桌之间交换修改作文，请你修改你同桌写的以下作文。文中共有10处语言错误，每句中最多有两处。错误仅涉及一个单词的增加、删除或修改。增加：在缺词处加一个漏字符号(∧)，并在其下面写出该加的词。删除：把多余的词用(＼)划掉。修改：在错的词下画一横线，并在该词下面写出修改后的词。注意：1、每处错误及其修改均仅限一词；2、只允许修改10处，多者（从第11处起）不计分。Questioningcanleadtofindananswer．Ifweareinhabitofraisingdoubtsastoifwhatwearetoldistrue,wecanfindthecorrectanswerandlearnmore．Twoyearsago,ourteacherofferedtousananswertoadifficultmathprobleminclass．Althoughtheanswerseemedalittlestrangely,nobodybutIdoubtedit．Thinkingthatmysolutionmightbewrong,Icarefullyanalyzetheproblem．Halfanhourlate,Im