高中英语Module4SectionⅠⅠntroduction＆ReadingPrereading课件外研版必修3.ppt

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1、Module4SectionⅠStep1Step2Step3Step4Step51．Haveyouevenbeencaughtinasandstorm?Whatdoyouthinkisthebestwaytopreventasandstorm?2．Doyouknowabouttheduststorm?Doyouknowwhatdamageaduststormmaycause?Duststormsdon‘tjusthappeninthemiddleofthedesert.Theyhappeninanydryareawhereloosedirtcanbeeasilypickedup.Grain

2、sofsandthrownintotheairbythewindusuallyfallbackdowntothegroundafterafewhours.Smallerbitsofparticles(颗粒)stayintheairforaweekorlongerandcanbeblownthousandsofmilesaway.DustfromtheSaharadesertisalwaysblownacrosstheAtlantic,causingbrightredsunrisesandsunsetsinMiami.Thedustdoesn‘tstopthere.Itkeepstravel

3、ingasfarastheCaribbeanandtheAmazonBasin.Aduststormisastrong,violentwindthatcarriesfineparticleslikeclay,dustandothermaterialsforlongdistances.Thefineparticlesdancearoundintheairduringthestorm.Thescarythingaboutaduststormisthattheycanspreadoverhundredsofmilesandriseover10,000feet(305meters)－wellove

4、rtheheightofatelephonepole.Theyalsohavewindspeedsofatleast25milesperhour(40kilometers),whichmaybenotstrongenoughtoblowthefeathersoffachickenbutstillsomethingworthavoiding.Don‘tbesurprisedifyousuddenlyseeaduststormheadingyourway.Duststormsusuallyarrivewithoutwarning.Thedustisblinding,makingdrivingi

5、mpossible.Oftentheyonlylastforafewminutesbutstormsusuallyleaveseriouscaraccidentsbehind.Ifyou’reinacarduringaduststorm,remindthedrivertopullovertothesideoftheroadandturnofftheheadlights.Neverstopinthemiddleoftheroad.Duringthe1960stherewereeightduststormsthatcausedsomeseriousdamage.RecentlyAustrali

6、awashavingproblemswithduststorms.ResearcherssaidthestormscostAustraliaabout20milliondollarsayearinmedicalbillsbecauseofdiseasescausedbyduststorms.Inmildduststormsit‘sstillpossibletowalkaroundalthoughyouwouldn’twantto.Thewindcarryingthedustwillleavethingslookingliketheywerejusthitbyatornado.Thebest

7、thingtodoisfindsafecoverinabuildingorstayinyourcar.Ⅰ.Whenlookingatthefollowingpictures,whatmayoccurinyourmind?Sandstormsofcourse!Doyouknowtheharmfuleffectsofsandstorms?AsfarasIknow,sandstormscan__________________