雅思阅读模拟试题

本文格式为Word版，下载可任意编辑——雅思阅读模拟试题雅思的阅读试题是雅斟酌试的一个难点，下面，我们一起来练习一份雅思的模拟题。

Sunsfickleheartmayleaveuscold

25January2022

FromNewScientistPrintEdition.

StuartClark

1.Theresadimmerswitchinsidethesunthatcausesitsbrightnesstoriseandfallontimescalesofaround100，000years-exactlythesameperiodasbetweeniceagesonEarth.Sosaysaphysicistwhohascreatedacomputermodelofourstarscore.

2.RobertEhrlichofGeorgeMasonUniversityinFairfax，Virginia，modelledtheeffectoftemperaturefluctuationsinthesunsinterior.Accordingtothestandardview，thetemperatureofthesunscoreisheldconstantbytheopposingpressuresofgravityandnuclearfusion.However，Ehrlichbelievedthatslightvariationsshouldbepossible.

3.HetookashisstartingpointtheworkofAttilaGrandpierreoftheKonkolyObservatoryoftheHungarianAcademyofSciences.In2022，Grandpierreandacollaborator，Gborgoston，calculatedthatmagneticfieldsinthesunscorecouldproducesmallinstabilitiesinthesolarplasma.Theseinstabilitieswouldinducelocalisedoscillationsintemperature.

4.Ehrlichsmodelshowsthatwhilstmostoftheseoscillationscanceleachotherout，somereinforceoneanotherandbecomelong-livedtemperaturevariations.Thefavouredfrequenciesallowthesunscoretemperaturetooscillatearounditsaveragetemperatureof13.6millionkelvinincycleslastingeither100，000or41，000years.Ehrlichsaysthatrandominteractionswithinthesunsmagneticfieldcouldflipthefluctuationsfromonecyclelengthtotheother.

5.ThesetwotimescalesareinstantlyrecognisabletoanyonefamiliarwithEarthsiceages：forthepastmillionyears，iceageshaveoccurredroughlyevery100，000years.Beforethat，theyoccurredroughlyevery41，000years.

6.MostscientistsbelievethattheiceagesaretheresultofsubtlechangesinEarthsorbit，knownastheMilankovitchcycles.OnesuchcycledescribesthewayEarthsorbitgraduallychangesshapefromacircletoaslightellipseandbackagainroughlyevery100，000years.ThetheorysaysthisalterstheamountofsolarradiationthatEarthreceives，triggeringtheiceages.However，apersistentproblemwiththistheoryhasbeenitsinabilitytoexplainwhytheiceageschangedfrequencyamillionyearsago.

7."InMilankovitch，thereiscertainlynogoodideawhythefrequencyshouldchangefromonetoanother，'saysNeilEdwards，aclimatologistattheOpenUniversityinMiltonKeynes，UK.NoristhetransitionproblemtheonlyonetheMilankovitchtheoryfaces.EhrlichandothercriticsclaimthatthetemperaturevariationscausedbyMilankovitchcyclesaresimplynotbigenoughtodriveiceages.

8.However，EdwardsbelievesthesmallchangesinsolarheatingproducedbyMilankovitchcyclesarethenamplifiedbyfeedbackmechanismsonEarth.Forexample，ifseaicebeginstoformbecauseofaslightcooling，carbondioxidethatwouldotherwisehavefounditswayintotheatmosphereaspartofthecarboncycleislockedintotheice.ThatweakensthegreenhouseeffectandEarthgrowsevencolder.

9.AccordingtoEdwards，thereisnolackofsuchmechanisms."Ifyouaddtheireffectstogether，thereismorethanenoughfeedbacktomakeMilankovitchwork，'hesays."Theproblemnowisidentifyingwhichmechanismsareatwork.'ThisiswhyscientistslikeEdwardsarenotyetreadytogiveuponthecurrenttheory."Milankovitchcyclesgiveusiceagesroughlywhenweobservethemtohappen.Wecancalculatewhereweareinthecycleandcompareitwithobservation，'hesays."Icantseeanywayoftesting[Ehrlichs]ideatoseewhereweareinthetemperatureoscillation.'

10.Ehrlichconcedesthis."Ifthereisawaytotestthistheoryonthesun，Icantthinkofonethatispractical，'hesays.Thatsbecausevariationover41，000to100，000yearsistoogradualtobeobserved.However，theremaybeawaytotestitinotherstars：reddwarfs.Theircoresaremuchsmallerthanthatofthesun，andsoEhrlichbelievesthattheoscillationperiodscouldbeshortenoughtobeobserved.Hehasyettocalculatethepreciseperiodortheextentofvariationinbrightnesstobeexpected.

11.NigelWeiss，asolarphysicistattheUniversityofCambridge，isfarfromconvinced.HedescribesEhrlichsclaimsas"utterlyimplausible'.EhrlichcountersthatWeisssopinionisbasedonthestandardsolarmodel，whichfailstotakeintoaccountthemagneticinstabilitiesthatcausethetemperaturefluctuations.

Questions1-4

CompleteeachofthefollowingstatementswithOneorTwonamesofthescientistsfromtheboxbelow.

WritetheappropriatelettersA-Einboxes1-4onyouranswersheet.

A.AttilaGrandpierre

B.Gborgoston

C.NeilEdwards

D.NigelWeiss

E.RobertEhrlich

1claimsthereadimmerswitchinsidethesunthatcausesitsbrightnesstoriseandfallinperiodsaslongasthosebetweeniceagesonEarth.

2calculat