人教版英语必修五课文电子版.docx

人教版英语必修五课文电子版.docx

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UnitlGREATSCIENTISTS

JOHNSNOWDEFEATS“KINGCHOLERA,,

JohnSnowwasafamousdoctorinLondon—soexpert,indeed,thatheattendedQueenVictoriaasherpersonalphysician.Buthebecameinspiredwhenhethoughtabouthelpingordinarypeopleexposedtocholera.Thiswasthedeadlydiseaseofitsday.Neitheritscausenoritscurewasunderstood.Somanythousandsofterrifiedpeoplediedeverytimetherewasanoutbreak.JohnSnowwantedtofacethechallengeandsolvethisproblem.Heknewthatcholerawouldneverbecontrolleduntilitscausewasfound.

Hebecameinterestedintwotheoriesthatpossiblyexplainedhowcholerakilledpeople.Thefirstsuggestedthatcholeramultipliedintheair,acloudofdangerousgasfloatedarounduntilitfounditsvictims.Fromthestomachthediseasequicklyattackedthebodyandsoontheaffectedpersondied.

JohnSnowsuspectedthatthesecondtheorywascorrectbutheneededevidence.SowhenanotheroutbreakhitLondonin1854,hewasreadytobeginhisenquiry.Asthediseasespreadquicklythroughpoorneighbourhoods,hebegantogatherinformation.Intwoparticularstreets,thecholeraoutbreakwassoseverethatmorethan500peoplediedintendays.Hewasdeterminedtofindoutwhy.

Firsthemarkedonamaptheexactplaceswhereallthedeadpeoplehavelived.Thisgavehimavaluableclueaboutthecauseofthedisease.ManyofthedeathswerenearthewaterpumpinBroadStreet（especiallynumbers163738and40）.Healsonoticedthatsomehouses（suchas20and21BroadStreetand8and9CambridgeStreet）hadhadnodeaths.Hehadnotforeseenthis,sohemadefurtherinvestigations.Hediscoveredthatthesepeopleworkedinthepubat7CambridgeStreet.Theyhadbeengivenfreebeerandsohadnotdrunkthewaterfromthepump.Itseemedthatthewaterwastoblame.

Next,JohnSnowlookedintothesourceofthewaterforthesetwostreets.HefoundthatitcamefromtheriverpollutedbythedirtywaterfromLondon.HeimmediatelytoldtheastonishedpeopleinBroadStreettoremovethehandlefromthepumpsothatitcouldnotbeused.Soonaftenvardsthediseasesloweddown.Hehadshownthatcholerawasspreadbygennsandnotinacloudofgas.

InanotherpartofLondon,hefoundsupportingevidencefromtwootherdeathsthatwerelinkedtotheBroadStreetoutbreak.Awoman,whohadmovedawayfromBroadStreet,likedthewaterfromthepumpsomuchthatshehaditdeliveredtoherhouseeveryday.Bothsheandherdaughterdiedofcholeraafterdrinkingthewater.WiththisextraevidenceJohnSnowwasabletoannouncewithcertaintythatpollutedwatercarriedthevirus.

Topreventthisfromhappeningagain,JohnSnowsuggestedthatthesourceofallthewatersuppliesbeexamined.Thewatercompanieswereinstructednottoexposepeopletopollutedwateranymore.Finally"KingCholera,,wasdefeated.

COPERNICUS,REVOLUTIONAYTHEORY

NicolausCopernicuswasfrightenedandhismindwasconfused.Althoughhehadtriedtoignorethem,allhismathematicalcalculationsledtothesameconclusion:

thattheearthwasnotthecentreofthesolarsystem.Onlyifyouputthesuntheredidthemovementsoftheotherplanetsintheskymakesense.YethecouldnottellanyoneabouthistheoryasthepowerfulChristianChurchwouldhavepunishedhimforevensuggestingsuchanidea.TheybelievedGodhadmadetheworldandforthatreasontheearthwasspecialandmustbethecentreofthesolarsystem.

Theproblemarosebecauseastronomershadnoticedthatsomeplanetsintheskyseemedtostop,movebackwardandthengoforwardinaloop.Othersappearedbrighterattimesandlessbrightatothers.Thiswasverystrangeiftheearthwasthecentreofthesolarsystemandallplanetswentaroundit.

Copernicushadthoughtlongandhardabouttheseproblemsandtriedtofindananswer.Hehadcollectedobservationsofthestarsandusedallhismathematicalknowledgetoexplainthem.Butonlynewtheorycoulddothat.Sobehveen1510and1514heworkedonit,graduallyimprovinghistheoryuntilhefeltitwascomplete.

In1514heshoweditprivatelytohisfriends.Thechangeshemadetotheoldtheorywererevolutionary.Heplacedafixedsunatthecentreofthesolarsystemwiththeplanetsgoingrounditandonlythemoonstillgoingaroundtheearth.Healsosuggestedthattheearthwasspinningasitwentaroundthesunandthisexplainedchangesinthemovementoftheplanetsandinthebrightnessofthestars.Hisfriendswereenthusiasticandencouragedhimtopublishhisideas,butCopernicuswascautious.HedidnotwanttobeattackedbytheChristianChurch,soheonlypublisheditashelaydyingin1543.

Certainlyhewasrighttobecareful.TheChristianChurchrejectedhistheory,sayingitwasagainstGod'sideaandpeoplewhosupporteditwouldbeattacked.YetCopernicus'theoryisnowthebasisonwhichallourid