Warmingup、Pre-reading、Reading、Comprehending (15).ppt

Warmingup、Pre-reading、Reading、Comprehending (15).ppt

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时间:2020-01-26

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1、Unit2SailingtheoceansReading选修九Pre-readingLookatthepicturesonpage11.Thenanswerthequestions.compassAstrolabe(星盘)Sextant(六分仪)sea/nauticalchart1Howdoyouthinkseamenfoundtheirwaybeforemodernaccuratemethodsofnavigationwereinvented?Keptclosetotheshore,usednaturesuchasthes

2、un,wind,birds,tide,etc,tohelpthem,andusedsomeoftheinstrumentsincludingacompass,astrolabe,etc.2Whichdoyouthinkwaseasiertoworkout:latitudeorlongitude?Latitude,becauseitwasusedtomeasurehowfaryouhadtravelledfromlandonastraightline.Itwasdiscoveredalongtimebeforelongitud

3、e.3Canyouidentifytheseearlynavigationalinstrumentsseamenusedandexplainhowtheyareused?1_________________________2_________3_________4________________________compass(inancientChina)astrolabesextantsea/nautical/marinechart4Whichonesdoyouthinkarestillusedtoday?Seachart

4、sarestillusedtoday.aquadrant(四分仪)aspecialtoolfortellingthepositionoftheshipinrelationtothesunandvariousstarsanastrolabemeasurehowhighstarswereabovethehorizonearlynavigationalinstrumentsanupdatednavigationalinstrumenttomeasuretheanglebetweentwofixedpointsoutsidethes

5、hipsextantabearingcircle方位圆thefirstinstrumenttomeasurethesun’spositionandthesun’sshadowSAILINGTHEOCEANSReadingNowreadaboutwhatnavigationwaslikebeforemoderninstrumentswereused.1Whatistheuseofabearingcircle,astrolabe,quadrantorsextant?()Whatistheuseofacompass?()Atose

6、tthecourseoftheshipBtomeasurethepositionoftheshipCtomeasurethespeedoftheshipDtotellthetimeBAComprehending1Readthepassageandanswerthefollowingquestions.Speedandtimeareimportantinfindingoutthelongitudeofashipbecausetheearthmovesfifteendegreeswestwardseveryhour.Ifyouk

7、nowyourdirection,speedandtime,youcanworkouttheapproximatelongitudeorchangeinyourpositioninrelationtothestars.Whyarespeedandtimeimportantinworkingoutthelongitudeofaship?Thepositionofthesunandstarsareusefulforworkingoutlatitudebecausetheyarefixedpointsintheskyandthei

8、rmovementsinrelationtotheeartharealreadyknown.Sotheycanbeusedtomeasureaship'sposition.3Whyisthepositionofthesunandvariousstarsusefulforworkingout

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