英语六级冲刺阅读训练及答案(20篇).doc

英语六级冲刺阅读训练及答案(20篇).doc

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一

TheEarthcomprisesthreeprincipallayers:

thedense,iron-richcore,themantlemadeofsilicate（硅酸盐）thataresemi-moltenatdepth,andthethin,solid-surfacecrustTherearetwokindsofcrust,aloweranddenseroceaniccrustandanupper，lightercontinentalcrustfoundoveronlyabout40percentoftheEarth'ssurface.Therocksofthecrustareofverydifferentages.Somecontinentalrocksareover3,000millionyearsold,whilethoseoftheoceanfloorarelessthan200millionyearsold.Thecrustsandthetop,solidpartofthemantle,totalingabout70to100kilometersinthickness,atpresentappeartoconsistofabout15rigidplates,7ofwhichareverylarge.Theseplatesmoveoverthesemi-moltenlowermantletoproduceallofthemajortopographical（地形学的）featuresoftheEarth.Activezoneswhereintensedeformationoccurareconfinedtothenarrow,interconnectingboundariesofcontactoftheplates.

　　Therearethreemaintypesofzonesofcontact:

spreadingcontactswhereplatesmoveapart,convergingcontactswhereplatesmovetowardseachother,andtransformcontactswhereplatesslidepasteachother.NewoceaniccrustisformedalongoneormoremarginsofeachplatebymaterialissuingfromdeeperlayersoftheEarth'scrust,forexample,byvolcaniceruptions（爆发）oflava（火山熔岩）atmid-oceanridges.Ifatsuchaspreadingcontactthetwoplatessupportcontinents，arift（裂缝）isformedthatwillgraduallywidenandbecomefloodedbythetea.TheAtlanticOceanformedlikethisastheAmericanandAfro-Europeanplatesmovedinoppositedirections.Whentwoplatescarryingcontinentscollide,thecontinentalblocks,toolighttobedrawndown,continuetofloatandthereforebuckle（起褶皱）toformamountainchainalongthelengthofthemarginoftheplates.

　　练习题：

　　Choosecorrectanswerstothequestion:

　　1.TheEarth’scrust______.

　　A.canbeclassifiedintotwotypes

　　B.isformedalongthemarginsoftheplates

　　C.consistsofsemi-moltenrocks

　　D.isabout70to100kilometersthick

　　2.The15platesoftheEarthareformedfrom___.

　　A.theoceaniccrustsandcontinentalcrusts

　　B.thecrustsandthemantle

　　C.thecrustsandthetopandsolidpartofthemantle

　　D.thecontinentalcrustsandthesolidpartofthemantle

　　3.Seriously-deformedzonesappear_______

　　A.wheneverthecrustsmoveovermantle

　　B.whentheplatesmovetowardseachother

　　C.inthenarrowboundarieswheretwoplatesmeet

　　D.tobethemajortopographicalfeatureoftheEarth

　　4.Accordingtothesecondparagraph,theformationoftheAtlanticOceanistheexampleof_______.

　　A.spreadingcontacts

　　B.theinfluenceofvolcaniceruptions

　　C.convergingcontacts

　　D.transformcontacts

　　5.Thispassageisprobably_______.

　　A.anewspaperadvertisement

　　B.achapterofanovel

　　C.anexcerptfromatextbook

D.ascientificreportofnewfindings

二

AremarkablevarietyofinsectsliveinthisplanetMorespeciesofinsectsexistthanallotheranimalspeciestogether.Insectshavesurvivedonearthformorethan300millionyears,andmaypossesstheabilitytosurviveformillionsmore.

　　Insectscanbefoundalmosteverywhere--onthehighestmountainsandonthebottomofrushingstreams,inthecoldSouthPoleandinbubblinghotsprings.Theydigthroughtheground,jumpandsinginthetrees,andrunanddanceintheair.Theycomeinmanydifferentcolorsandvariousshapes.Insectsareextremelyusefultohumans,pollinating（授粉）ourcropsaswellasflowersinmeadows,forests,desertsandotherareas.Butlicksandsomeinsects,suchasmosquitoesandfleas,cantransmitdisease.

　　Therearemanyreasonswhyinsectsaresosuccessfulatsurviving.Theiramazingabilitytoadaptpermitsthemtoliveinextremerangesoftemperaturesandenvironments.Theoneplacetheyhavenotyetbeenfoundtoanymajorextentisintheopenoceans.Insectscansurviveonawiderange,ofnaturalandartificialfoods—paint,pepper,glue,books,grain,cotton，otherinsects,plantsandanimalsBecausetheyaresmalltheycanhideintinyspaces.

　　Astrong,hardbutflexibleshellcoverstheirsoftorgansandisresistanttochemicals,waterandphysicalimpact.Theirwingsgivethemtheoptionofflyingawayfromdangeroussituationsortowardfoodormales.Also,insectshaveanenormousreproductivecapacity:

AnAfricanantqueencanlayasmanyas43,000eggsaday.

　　Anotherreasonfortheirsuccessisthestrategyofprotectivecolor.Aninsectmayberightbeforeoureyes,butnearlyinvisiblebecauseitiscleverlydisguisedlikeagreenleaf,lumpofbrownsoil,graylichen（青苔）,aseedorsomeothernaturalobjectSomeinsectsusebright,boldcolorstosendwarningsignalsthattheytastebad,stingorarepoison.Othershavewingpatternsthatlookliketheeyesofahugepredator,bitter-tastinginsects;hungryenemiesarefooledintoavoidingthem.

　　练习题：

　　Choosecor