2015年8月29日雅思閱讀考情回顧

雅思閱讀機(jī)經(jīng)一、考試時(shí)間：2015829日（周六）本次考試是暑最后一場(chǎng)考試，很多暑假班的學(xué)生都報(bào)考了本場(chǎng)考試作為學(xué)習(xí)成果的驗(yàn)，好消息是本次考試難度的確不高，但對(duì)于試圖通過(guò)“”的學(xué)生來(lái)說(shuō)，傳言中的察無(wú)法也無(wú)必要全面回憶本次考情回顧還是依照卷為參考第一篇Energyfromthe篇講得更全面。第二篇DesertFormation，講沙漠的形成，可參考劍七第三套第三篇的 第一套第二篇的AirTrafficControlintheUSA有相似點(diǎn)。Passage1:EnergyfromtheOcean，海洋能源Passage2:DesertFormation，沙漠化Passage3:InnovativeAircraft海洋中可以利用的4種能源，分別為tidalpower,marinecurrentpower,wavepower,oceanthermalenergy海洋中可以利用的4種能源，分別為tidalpower,marinecurrentpower,wavepower,oceanthermalenergy。題型分布與多選3題+匹配題5題+填空題5題在海洋中建立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題型分布與題型分布與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題型分布與5題型分布與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