6大学英语六级考试全真模拟卷A.docx
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6大学英语六级考试全真模拟卷A
CollegeEnglishPracticeTest1
PartIWriting(30minutes)
Directions:
Inthispart,youareallowed30minutestowriteashortessayentitledAnEye-witnessAccountofaTrafficAccident.Youshouldwriteatleast150wordsfollowingtheoutlinegivenbelow.
1.车祸发生的时间及地点;
2.你所见到的车祸情况;
3.你对车祸原因的分析。
PartⅡReadingComprehension(SkimmingandScanning)(15minutes)
ABriefHistoryofClock
Clocks
Atbest,historiansknowthat5,000-6,000yearsago,greatcivilizationsintheMiddleEastandNorthAfricastartedtoexamineformsofclock-makinginsteadofworkingwithonlythemonthlyandannualcalendar.Littleisknownonexactlyhowtheseformsworkedorindeedtheactualdeconstructionofthetime,butithasbeensuggestedthattheintentionwastomaximizetimeavailabletoachievemoreasthesizeofthepopulationgrew.Perhapssuchfutureperiodsoftimewereintendedtobenefitthecommunitybyallottingspecificlengthsoftimetotasks.Wasthisthebeginningoftheworkingweek?
SunClocks
Withthedisappearanceofanyancientcivilization,suchastheSumerianculture,knowledgeisalsolost.Whilstwecanonlyhypothesizeonthereasonsofwhytheequivalenttothemodernwristwatchwasnevercompleted,weknowthattheancientEgyptianswerenexttolayoutasystemofdividingthedayintoparts,similartohours.
"Obelisks"(tallfour-sidedtaperedmonuments)werecarefullyconstructedandevenpurposefullygeographicallylocatedaround3500BC.AshadowwaseastastheSunmovedacrosstheskybytheobelisk,whichitappearswasthenmarkedoutinsections,allowingpeopletoclearlyseethetwohalvesoftheday.Someofthesectionshavealsobeenfoundtoindicatethe"year"slongestandshortestdays,whichitisthoughtweredevelopmentsaddedlatertoallowidentificationofotherimportanttimesubdivisions.
AnotherancientEgyptian"shadowclock"or"sundial"hasbeendiscoveredtohavebeeninusearound1500BC,whichallowedthemeasuringofthepassageof"hours".Thesectionsweredividedintotenparts,Withtwo"twilighthours"indicated,occurringinthemorningandtheevening.Forittoworksuccessfullythenatmiddayornoon,thedevicehadtobeturned180degreestomeasuretheafternoonhours.
WaterClocks
"Waterclocks"wereamongtheearliesttimekeepingdevicesthatdidn'tusetheobservationofthecelestialbodiestocalculatethepassageoftime.TheancientGreeks,itisbelieved,beganusingwaterclocksaround325BC.Mostoftheseclockswereusedtodeterminethehoursofthenight,butmayhavealsobeenusedduringdaylight.Aninherentproblemwiththewaterclockwasthattheywerenottotallyaccurate,asthesystemofmeasurementwasbasedontheflowofwatereitherinto,oroutof,acontainerwhichhadmarkersaroundthesides.Anotherverysimilarformwasthatofabowlthatsankduringaperiodasitwasfilledofwaterfromaregulatedflow.ItisknownthatwaterclockswerecommonacrosstheMiddleEast,andthatthesewerestillbeingusedinNorthAfricaduringtheearlypartofthetwentieth-century.
MechanicalClocks
In1656,"ChristianHuygens'(Dutchscientist),madethefirst"Pendulum(钟摆)clock",withamechanismusinga"natural"periodofoscillation(振幅)."GalileoGalilei"iscredited,inmosthistoricalbooks,forinventingthependulumasearlyas1582,buthisdesignwasnotbuiltbeforehisdeath.Huygens'clock,whenbuilt,hadanerrorof"lessthanonlyoneminuteaday".Thiswasamassiveleapinthedevelopmentofmaintainingaccuracy,asthishadpreviouslyneverbeenachieved.Laterrefinementstothependulumclockreducedthismarginoferrorto"lessthan10secondsaday".
Themechanicalclockcontinuedtodevelopuntiltheyachievedanaccuracyof"ahundredth-of-a-secondaday",whenthependulumclockbecametheacceptedstandardinmostastronomicalobservatories.
QuartzClocks
Therunningofa"Quartzclock"isbasedonthepiezoelectricpropertyofthequartzcrystal.Whenanelectricfieldisappliedtoaquartzcrystal,itactuallychangestheshapeofthecrystalitself,Ifyouthensqueezeitorbendit,anelectricfieldisgenerated.Whenplacedinanappropriateelectroniccircuit,thisinteractionbetweenthemechanicalstressandtheelectricalfieldcausesthecrystaltovibrate,generatingaconstantelectricsignalwhichcanthenbeusedforexampleonanelectronicclockdisplay.Thefirstwrist-watchesthatappearedinmassproductionused"LED","LightEmittingDiode"displays.Bythe1970'stheseweretobereplacedbya"LCD","LiquidCrystalDisplay".
Quartzclockscontinuetodominatethemarketbecauseoftheaccuracyandreliabilityoftheperformance,alsobeinginexpensivetoproduceonmassscale.Thetimekeepingperformanceofthequartzclockhasnowbeensurpassedbythe"Atomicclock".
AtomicClocks
Scientistsdiscoveredsometimeagothatatomsandmoleculeshave"resonances"andthateachchemicalelementandcompoundabsorbsandemits"electromagneticradiation"withinitsowncharacteristic"frequencies".Thiswearetoldishighlyaccurateevenover"TimeandSpace".
Thedevelopmentofradarandthesubsequentexperimentationwithhighfrequencyradiocommunicationsduringthe1930sand1940screatedavastamountofknowledgeregarding"electromagneticwaves",alsoknownas"microwaves".whichinteractwiththeatoms.ThedevelopmentofatomicclocksfocusedfirstlyonmicrowaveresonancesinthechemicalAmmoniaanditsmolecules.In1957."NIST".the"NationalInstituteofStandardsandTechnology",completedaseriesoftestsusinga"CesiumAtomicBeam"device,followedbyasecondprogramofexperimentsbyNISTinordertohavesomethingforcomparisonwhenworkingattheatomiclevel.By1960,astheoutcomeoftheprograms,"CesiumTimeStandards"wereincorporatedastheofficialtimekeepingsystematNIST.
The"Naturalfrequency"recognizedcurrentlyisthemeasurementoftime.usedbyallscientists,definestheperiodof"onesecond"asexactly"9,192,631,770Oscillations"or"9,192,631,770CyclesoftheCesiumAtom'sResonantFrequency".Fromthe"Macrocosm",or"PlanetaryAlignment",tothe"Microcosm",or"AtomicFrequency",thecesiumnowmaintainsaccuracywithadegreeoferrortoabout"one-millionthofasecondperyear".
Muchofmodernlifehascometodependonsuchprecisemeasurementsoftime.Thedayislongpastwhenwecouldgetbywithatimepiece(钟)accuratetothenearestquarterhour.Transportation,financialmarkets,communication,manufacturing,electricpowerandmanyothertechnologieshavebecomedependentonsuper-accurateclocks.Scientificresearchandthedemandsofmoderntechnologycontinueredriveoursearchforevermoreaccuracy,ThenextgenerationofCesiumTimeStandardsispresentlyunderdevelopmentatNIST's"BoulderLaboratory"andotherlaboratoriesaroundtheworld.
SomethingtoRemember
Theonlythingthatshouldberememberedduringallthistechnologicaldevelopmentisthatweshouldneverlosetheabilitytotellthetimeapproximatelybynaturalmeansandthepowersofdeductionwithoutrequiringcrutches(拐杖)toleanon.
OurconceptofTIMEandusingittogetherwithTECHNOLOGYstillhasroomforradicalreassessmentintermsofman'sevolutionarythinkingregardingourviewofthepast,ouronwardjourneyintothefutureandourconceptoftimeinrelationshiptouniverse.
1.Itissuggestedthat5,000-6,000yearsagopeopleintheMiddleEastandNorthAfricastartedtoallotspecificlengthsoftimetotasks.
2.AncientEgyptian"shadowclock"or"sundial"discoveredaround1500BC,couldmeasurepassageof"hours"automaticallyandcontinuously.
3."Waterclocks"wasthefirstdevicethatdidn'tusetheobservationofthecelestialbodiestocalculatethepassageoftime.
4.GalileoGalileibuiltthefirst"pendulumclock"asearlyas1656.
5.Waterclocksweremostlyusedtodetermine______.
6.Huygens'clock,amechanicalone,hadanerrorof"lessthanonlyoneminuteaday",whichwasamassiveleapinthedevelopmentof______.
7.SinceQuartzclocksarebothinexpensivetoproduceinmassscaleand______inperformance,theycontinuetodominatethemarket.
8.Scientificresearchandthe______continuetodriveoursearchforevermoreaccuracyintime.
9.Ofalltheclocksintroducedinthepassage,theonewiththemostaccuracyis______.
10.Nomatterhowadvancedthetechnologyofmeasuringtimewillbeweshouldneverlosetheabilitytotellthetimeapproximatelyby______.
PartⅢListeningComprehension(35minutes)
SectionA
Questions11to18arebasedontheconversationyouhavejustheard.
11.A)Thetransportationfarthetripisfree.
B)Theclassdidn'tenjoygoingonthefieldtrip.
C)Somepeoplemaynotgoonthetrip.
D)Alloftheclassmembersnavepaidthefee.
12.A)Takealotofmoney.B)Gotoadifferentrestaurant.
C)Don'tinviteJohn.D)Weardifferentclothes.
13.A)Theydidn'thaveggoodtalk.B)Theydecidedtogobyplane.
C)Theyweren'tabletotakeawalk.D)Theytalkedaboutgeology.
14.A)Shedoesn'tneedanumbrella.
B)Sheleftherumbrellainthecar.
C)Shecanholdherumbrellaovertheman'shead.
D)She'stheonlyonewhodoesn'thaveanumbrella.
15.A)Hewouldsendapostcardifhewentaway.
B)Hewouldbeabletotakeavacation.
C)Hehadalreadygonebacktowork.
D)Hedidn'twanttogotoFlorida.
16.A)ThemanwantstomovetoSanFrancisco,butthewomandoesn'tagree.
B)Themanthinksit'stoocoldtomovetoSanFrancisco.
C)Thewomanagreeswiththeman'sidea.
D)Thewomandoesn'twanttomovebecausethechildrenwillhavenofun.
17.A)Togotothemovies.B)Togooutforlunch.
C)Tolookinthenewspaper