教材文本 unit 2 reading

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1、Unit2SailingtheOceansPre-readingLookatthepictures.Thenanswerthequestions.1Howdoyouthinkseamenfoundtheirwaybeforemodernaccuratemethodsofnavigationwereinvented?2Whichdoyouthinkwaseasiertoworkout:latitudeorlongitude?3Canyouidentifytheseearlynavigationalinstrumentsseamenusedandexplainhowtheyareused?1

2、______________2______________3______________4______________4Whichonesdoyouthinkarestillusedtoday?Nowreadaboutwhatnavigationwaslikebeforemoderninstrumentswereused.ReadingSAILINGTHEOCEANSWemaywellwonderhowseamenexploredtheoceansbeforelatitudeandlongitudemadeitpossibletoplotaship’spositiononamap.The

3、voyagesoftravellersbeforethe17thcenturyshowthattheywerenotatthemercyoftheseaeventhoughtheydidnothavemodernnavigationalaids.Sohowdidtheynavigatesowell?Readthesepagesfromanencyclopedia.Pagel:UsingnaturetohelpKeepingalongsidethecoastlineThisseemstohavebeenthefirstandmostusefulformofexplorationwhichc

4、arriedtheminimumamountofrisk.Usingcelestialbodies●NorthStarAttheNorthPoletheNorthStarisatitshighestpositioninthesky,butattheequatoritisalongthehorizon.Soaccomplishednavigatorswereabletouseittoplottheirpositions.●SunOnacleardayespeciallyduringthesummerthesailorscouldusethesunoverheadatmiddaytonavi

5、gateby.Theycanusetheheightofthesuntoworkouttheirlatitude.●CloudsSeacaptainsobservedthecloudsoverislands.Thereisaspecialcloudformationwhichindicatesthereislandcloseby.Usingwildlife●SeaweedSailorsoftensawseaweedintheseaandcouldtellbythecolourandsmellhowlongithadbeenthere.Ifitwasfreshandsmelledstron

6、gly,thentheshipwasclosetoland.●BirdsSeabirdscouldbeusedtoshowthewaytolandwhenitwasnowheretobeseen.Intheeveningnestingbirdsreturntolandandtheirnests.Soseamencouldfollowthebirdstolandeveniftheywereoffshoreandintheopensea.Usingtheweather●FogFoggathersatseaaswellasoverstreamsorrivers.Seamenusedittohe

7、lpidentifythepositionofastreamorriverwhentheywereclosetoland.●WindsWiseseamenusedthewindstodirecttheirsailing.Theycouldacceleratethespeed,buttheycouldalsobedangerous.SotheVikingswouldobservethewindsbeforeandduringtheir