2015年8月29日雅思阅读考情回顾

雅思阅读机经一、考试时间：2015829日（周六）本次考试是暑最后一场考试，很多暑假班的学生都报考了本场考试作为学习成果的验，好消息是本次考试难度的确不高，但对于试图通过“”的学生来说，传言中的察无法也无必要全面回忆本次考情回顾还是依照卷为参考第一篇Energyfromthe篇讲得更全面。第二篇DesertFormation，讲沙漠的形成，可参考剑七第三套第三篇的 第一套第二篇的AirTrafficControlintheUSA有相似点。Passage1:EnergyfromtheOcean，海洋能源Passage2:DesertFormation，沙漠化Passage3:InnovativeAircraft海洋中可以利用的4种能源，分别为tidalpower,marinecurrentpower,wavepower,oceanthermalenergy海洋中可以利用的4种能源，分别为tidalpower,marinecurrentpower,wavepower,oceanthermalenergy。题型分布与多选3题+匹配题5题+填空题5题在海洋中建立Tidalpowernt的positiveA.ArangeofseaB.costofestablishingatidalpowerC.itishelpfultoestablishtransportationD.effectoffishandsomeothersealifeA.TidalB.CurrentC.ThermalwhichkindofenergyhasalreadybeensubjecttoasuccessfultrialAWhichkindofenergyhasbeenlargelyusedduringthepasttime?Whichkindofenergyhasfailedinanexperiment?Water,above30℃willbeTidalpower,Wavepower,Marinecurrentpower,Osmoticpower,Oceanthermalenergyaredifferentformsofrenewableoceanenergysourcesutilizedtodousefulwork—forexampleforelectricitygeneration,waterdesalination,orthepumofwater(intoreservoirs).OceanEnergy(orOceanpowerorMarineenergyorMarinepower)referstotheenergycarriedbyoceanwaves,tides,salinity,anddeepoceantemperaturedifferences.Themovementofwaterintheworld’soceanscreatesavaststoreofkineticenergy,orenergyinmotion.Thisenergycanbeharnessedtogenerateelectricitytopowerhomes,transportandindustries.Thetermmarineenergy passesbothwavepower—powerfromsurfacewaves,andtidalpower—obtainedfromthekineticenergyoflargebodiesofmovingwater.Offshorewindpowerisgenerallyconfusedasaformofmarineenergy,butisnotaswindpowerisderivedfromthewind,evenifthewindturbinesarecedoverwater.TidalTidalpowerisalsocalledtidalenergy,isaformofhydropowerthatconvertstheenergyoftidesintoelectricityorotherusefulformsofpower.houghnotyetwidelyused,tidalpowerhaspotentialforfutureelectricitygeneration.Tidesaremorepredictablethanwindenergyandsolarpower.Tidalenergyisextractedfromtherelativemotionoflargebodiesofwater.Periodicchangesofwaterlevels,andassociatedtidalcurrents,areduetothegravitationalattractionoftheSunandMoon.Greatertidalvariationortidalcurrentvelocitiescandramaticallyincreasethepotentialfortidalelectricitygeneration.Tidalstreamgenerators(orTSGs)makeuseofthekineticenergyofmovingwatertopowerturbines,inasimilarwaytowindturbinesthatusemovingair.Thismethodisgaininginpopularitybecauseofthelowercostandlowerecologicalimpactcomparedtotidalbarrages.Tidalbarragesmakeuseofthepotentialenergyinthedifferenceinheight(orhead)betweenhighandlowtides.Barragesareessentiallydamsacrossthefullwidthofatidalestuary,andsufferfromveryhighcivilinfrastructurecosts,aworldwideshortageofviablesitesandenvironmentalissuDynamictidalpower(orDTP)isatheoreticalgenerationtechnologythatwouldexploitaninctionbetweenpotentialandkineticenergiesintidalflows.Itproposesthatverylongdams(forexample:30–50kmlength)bebuiltfromcoastsstraightoutintotheseaorocean,withoutenclosinganarea.WaveWavepoweristhetransportofenergybyoceansurfacewaves,andthecaptureofthatenergytodousefulwork—forexampleforelectricitygeneration,waterdesalination,orthepumofwater(intoreservoirs).Wavepowerisdistinctfromthediurnalfluxoftidalpowerandthesteadygyreofoceancurrents.WavepowergenerationisnotcurrentlyawidelyemployedcommercialtechnologyalthoughtherehavebeenattemptsatusingMarineCurrentMarinecurrentpowerisaformofmarineenergyobtainedfromharnessingofthekineticenergyofmarinecurrents,suchastheGulfstream.Althoughnotwidelyusedatpresent,marinecurrentpowerhasanimportantpotentialforfutureelectricitygeneration.Marinecurrentsaremorepredictablethanwindandsolarpower.OsmoticOsmoticpowerorsalinitygradientpoweristheenergyavailablefromthedifferenceinthesaltconcentrationbetweenseawaterandriverwater.Twopracticalmethodsforthisarereverseelectrodialysis(RED)andpressuretardedosmosis.(PRO).Bothprocessesrelyonosmosiswithionspecificmembranes.Thekeywasteproductisbrackishwater.Thisbyproductistheresultofnaturalsthatarebeingharnessed:theflowoffreshwaterintoseasthataremadeupofsaltwater.OsmoticThermalOceanthermalenergyconversion(OTECorOTE)usesthedifferencebetweencoolerdeepandwarmershalloworsurfaceoceanwaterstorunaheatengineandproduceusefulwork,usuallyintheformofelectricity.Aheatenginegivesgreaterefficiencyandpowerwhenrunwithalargeperature题型分布与题型分布与1.Migration2.3.Soil4.5.206.利 研究沙漠沙漠形成是由于lackofrain.SoildegradationisbecauseofthefarmTheWestAfricastillnotrecoverfromthedroughts.Thedeserts,whichalreadyoccupyapproximaya oftheEarth'slandsurface,haveinrecentdecadesbeenincreasingatanalarmingpace.Theexpansionofdesertlikeconditionsintoareaswheretheydidnotpreviouslyexistiscalleddesertification.Ithasbeenestimatedthatanadditionalone- oftheEarth'slandsurfaceisthreatenedbythisDesertificationis plishedprimarilythroughthelossofstabilizingnaturalvegetationandthesubsequentacceleratederosionofthesoilbywindandwater.Insomecasestheloosesoilisblowncompleyaway,leavingastonysurface.Inothercases,thefinerparticlesmayberemoved,whilethesand-sizedparticlesareaccumulatedtoform ofsand.Evenintheareasthatretainasoilcover,thereductionofvegetationtypicallyresultsinthelossofthesoil'sabilitytoabsorbsubstantialtiesofwater.Theimpactofraindropsontheloosesoiltendstotransferfineclayparticlesintothetiniestsoilspaces,sealingthemandproducingasurfacethatallowsverylittlewaterpenetration.Waterabsorptionisgreatlyreduced;consequentlyrunoffisincreased,resultinginacceleratederosionrates.ThegradualdryingofthesoilcausedbyitsdiminishedabilitytoabsorbwaterresultsinthefurtherlossofsothatacycleofprogressivesurfacedeteriorationisInsomeregions,theincreaseindesertareasisoccurringlargelyastheresultofatrendtowarddrierclimaticconditions. gradualglobalwarminghasproducedanincreaseinaridityforsomeareasoverthepastfewthousandyears.TheprocessmaybeacceleratedinsubsequentifglobalwarmingresultingfromairpollutionseriouslyThereislittledoubt,however,thatdesertificationinmostareasresultsprimarilyfromhumanactivitiesratherthannaturalprocesses.Thesemiaridlandsborderingthedesertsexistinadelicateecologicalbalanceandarelimitedintheirpotentialtoadjusttoincreasedenvironmentalpressures.Expandingpopulationsaresubjectingthelandtoincreasingpressurestoprovidethemwithfoodandfuel.Inwetperiods,thelandmaybeabletorespondtothesestresses.Duringthedryperiodsthatarecommonphenomenaalongthedesertmargins,though,thepressureonthelandisoftenfarinexcessofitsdiminishedcapacity,anddesertificationresults.Fourspecificactivitieshavebeenidentifiedasmajorcontributorstothedesertificationprocesses:overcultivation,overgrazing,firewoodgathering,drierregionsaspopulationdensitieshavegrown.Theseregionsareespeciallylikelytohaveperiodsofseveredryness,sothatcropfailuresarecommon.Sincetheraisingofmostcropsnecessitatesthepriorremovalofthenaturalvegetation,cropfailuresleaveextensivetractsoflanddevoidofantcoverandsusceptibletowindandwatererosion.Theraisingoflivestockisamajoreconomicactivityinsemiaridlands,wheregrassesaregenerallythedominanttypeofnaturalvegetation.Theconsequencesofanexcessivenumberoflivestockgrazinginanareaarethereductionofthevegetationcoverandthetramplingandpulverizationofthesoil.ThisisusuallyfollowedbythedryingofthesoilandacceleratedFirewoodisthechieffuelusedforcookingandheatinginmanycountries.Theincreasedpressuresofexpandingpopulationshaveledtotheremovalofwoodyntssothatmanycitiesandtownsaresurroundedbylargeareascompleylackingintreesandshrubs.TheincreasinguseofdriedanimalwasteasasubstitutefuelhasalsohurtthesoilbecausethisvaluablesoilconditionerandsourceofntnutrientsisnolongerbeingreturnedtheThefinalmajorhumancauseofdesertificationissoilsalinizationresultingfromoverirrigation.Excesswaterfromirrigationsinksdownintothewatertable.Ifnodrainagesystemexists,thewatertablerises,bringingdissolvedsaltstothesurface.Thewaterevaporatesandthesaltsareleftbehind,creatingawhitecrustallayerthatpreventsairandwaterfromreachingtheunderlyingsoil.Theextremeseriousnessofdesertificationresultsfromthevastareasoflandandthetremendousnumbersofpeopleaffected,aswellasfromthegreatdifficultyofreversingorevenslowingtheprocess.Oncethesoilhasbeenremovedbyerosion,onlythepassageofcenturiesormillenniawillenablenewsoiltoform.Inareaswhereconsiderablesoilstillremains,though,arigorouslyendprogramoflandprotectionandcover-cropmaymakeitpossibletoreversethepresentdeteriorationofthe题型分布与5题型分布与5道+4道+5AirresourceswithintheCanadian shadsufferedfromalongperiodofneglectanddownsizingduringthelate1960sandearly1970sthatledtotheagingofmuchoftheirmilitaryequipment.Intheearly1970stheernmentcameunderincreasingpressurefromitsNATOalliestoredressthisimbalance.ThisperiodcametoanendinNovember1975after erningLiberalPartyofCanada'stenthNationalConventionsawareversingdefencebudgetcutbacksintheearly1970sandthebeginningofamodernizationprocessacrosstheentireCanadian structure;thisfollowedadecisioninSeptember1975thatsawallairresourceswithintheCanadian smergedintoanewentitycalledAirCommand( ).Astherehadbeenlittlemilitarycapitalexpenditureoverthepriorfiveyears,modernizingthe swouldbeanexpensiveprocess.Inordertolowerfiscalspendingfortheambitiousprogram,seriesofindividualprocurementprojectswereproposedtobespreadoverthefive-yearperiodfrom1977toDuringthe1970s,theCanadian swastaskedwithfourprimarymilitaryduties;airdefenceofNorthAmericaaspartofNORAD,anti-submarineandrelateddutiesintheNorthAtlanticaspartofNATO,asmallrolewithintheoverallland-structureofNATOinWesternEurope,andthespecialistroleofreinforcingNorwaywithonebrigadeandallrequiredair,seaandothersupportthatmightbeneededforthatmission(collectivelyknownas"CAST").Withtheexceptionofairtransport,equipmentforallofthesetaskswasdeemedtobelacking.Sixprocurementprojectsbecametheinitialfocusofthelate1970supgradeprocess.ForMaritimeCommand( )anew"LongRangePatrolAircraftProject"(LRPA)woulddramaticallyincreasetheiranti-submarinecapabilities,whileanew"PatrolFrigateProject"wouldsupplementtherecentlyprocuredandextremelycapableIroquoisclassdestroyer.CommandneededanewmainbattletorecetheoutdatedCenturionaswellasnewcommandandlog