英语六级冲刺阅读训练及答案(20篇).doc
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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
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