《大学英语(三)》作业

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1、大学英语（三）《大学英语（三）》作业PartI.ReadingComprehensionDirections:Therearethreepassagesinthispart.Eachpassageisfollowedbysomequestions.ForeachofthemtherearefourchoicesmarkedA,B,CandD.Youshoulddecideonthebestchoice.Passage1Inthesummerof1978anEnglishfarmernamedIanStevenswasdrivinghistractorthroughafieldo

2、fwheatwhenhediscoveredsomethingstrange.Someofhiswheatwaslyingflatontheground.Theflattened（被压平的）wheatformedacircleaboutsixmetersacross.Aroundthiscirclewerefoursmallercirclesofflattenedwheat.Inthefollowingyearsmoreandmoresimilarcircleswerefoundinafieldofwheatorcorn.Sopeoplecannothelpbutasktheq

3、uestion:Whatcausesthecircles?Atfirst,peoplesuspectedthatthecircleswereatrick.Toprovethatthecircleswereatrick,peopletriedtocopythem:theytriedtomakecirclesexactlyliketheonesthefarmershadfound.Theycouldn'tdoit.Theycouldn'tenterafieldofgrainwithoutleavingtracks,andtheycouldn'tflattenthegrainwith

4、outbreakingit.Thecirclesareapparentlynotatrick.Manypeoplebelievethatbeingsfromouterspacearemakingthecircles.Somethinkthatthebeingsaretryingtocommunicatewithusfromfarawayandthatthecirclesaremessagesfromthem.Othersbelievethatthebeingshaveactuallylandedonearthandthatthecirclesaremarksleftbythei

5、rspaceships.Severaltimespeoplereportedseeingstrangeflyingobjectsnearfieldswherecircleslaterappeared.Scientistssaythey'renotsurewhatcausesthem.Theyhavesuggestedseveraltheories.Forexample,somescientistssaythat"microbursts"ofwindcreatedthecircles.Amicroburstisadownwardrushofcoolair—thesamedownw

6、ardrushofairthatsometimescausesanairplanetocrash.Othersscientistssaythatforceswithintheearthcausethecirclestoappear.Butcirclesoftenappearinforms.Itishardtobelievethatanynaturalforcecouldcreatethoseforms.Andrecentlyfarmershavediscoverednotonlycirclesbutalsoothershapessuchastrianglesintheirfie

7、lds.Couldanynaturalforcecreatedaperfecttriangleinafieldofgrain?Inthesummerof1990somescientistsspentthreeweeksinthepartofEnglandwheremanycircleshaveappeared.Theyhadallthelatesthigh-techequipment.Thisequipment—worth1.8milliondollars—recordednothing.B