必修4Unit 2 Chemical or Organic Farming公开课优质获奖课件优质PPT.pptx

必修4Unit 2 Chemical or Organic Farming公开课优质获奖课件优质PPT.pptx

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Theyneed,+,+,+,Fertilizers?

Chemicalfertilizers,Naturalfertilizers,chemicalfarming,organicfarming,Predictwhatwewillknowfromthepassage.Wellknow.,ChCemheimcaiclaolorrOOrrggaanniiccFFaarrmmining?

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Task1Underlinethetopicsentenceofeachparagraph.,AWhataresomeoftheproblemscausedbychemicalfertilizers?

First,theydamagethelandbykillingthehelpfulbacteriaandpestsaswellastheharmfulones.Chemicalsalsostayinthegroundandundergroundwaterforalongtime.Thisaffectscropsand,therefore,animalsandhumans,sincechemicalsgetinsidethecropsandcannotjustbewashedoff.Thesechemicalsinthefoodsupplybuildupinpeoplesbodiesovertime.Manyofthesechemicalscanleadtocancerorotherillnesses.Inaddition,fruit,vegetablesandotherfoodgrownwithchemicalfertilizersusuallygrowtoofasttobefullofmuchnutrition.Theymaylookbeautiful,butinsidethereisusuallymorewaterthanvitaminsandminerals.,Task1Underlinethetopicsentenceofeachparagraph.,A.Whataresomeoftheproblemscausedbychemicalfertilizers?

B.C.D.,Task1Underlinethetopicsentenceofeachparagraph.,BWiththesediscoveries,somefarmersandmanycustomersarebeginningtoturntoorganicfarming.Organicfarmingissimplyfarmingwithoutusinganychemicals.Theyfocusonkeepingtheirsoilrichandfreeofdisease.Ahealthysoilreducesdiseaseandhelpscropsgrowstrongandhealthy.Organicfarmers,therefore,oftenpreferusingnaturalwastefromanimalsasfertilizer.Theyfeelthatthismakesthesoilintheirfieldsricherinmineralsandsomorefertile.Thisalsokeepstheair,soil,waterandcropsfreefromchemicals.,Task1Underlinethetopicsentenceofeachparagraph.,COrganicfarmingalsousemanyothermethodstokeepthesoilfertile.Theyoftenchangethekindofcropineachfieldeveryfewyears,forexample,growingcornorwheatandthenthenextyearpeasorsoybeans.Cropssuchaspeasorsoybeansputimportantmineralsbackintothesoil,makingitreadyforcropssuchaswheatorcornthatneedrichandfertilesoil.Organicfarmersalsoplantcropstousedifferentlevelsofsoil,forexample,plantingpeanutsthatusethegroundssurfacefollowedbyvegetablesthatputdowndeeproots.Someorganicfarmerspreferplantinggrassbetweencropstopreventwindorwaterfromcarryingawaythesoil,andthenleavingitinthegroundtobecomeanaturalfertilizerforthenextyearscrop.Thesemanydifferentorganicfarmingmethodshavethesamegoal:

togrowgoodfoodandavoiddamagingtheenvironmentorpeopleshealth.,Task1Underlinethetopicsentenceofeachparagraph.,DOverthepasthalfcentury,usingchemicalfertilizershasbecomeverycommoninfarming.Manyfarmerswelcomedthemasagreatwaytostopcropdiseaseandincreaseproduction.Recently,however,scientistshavebeenfindingthatlong-termuseofthesefertilizerscancausedamagetothelandand,evenmoredangerous,topeopleshealth.,Thetopicsentencesofeachparagraph:

Whataresomeoftheproblemscausedbychemicalfertilizers?

Withthesediscoveries,somefarmersandmanycustomersarebeginningtoturntoorganicfarming.Organicfarmersalsousemanyothermethodstokeepthesoilfertile.Recently,however,scientistshavebeenfindingthatlong-termuseofthesefertilizerscancausedamagetothelandandevenmoredangerous,topeopleshealth.Task2Putthefourparagraphsinorder.ABCD,Thetopicsentencesofeachparagraph:

Withthesediscoveries,somefarmersandmanycustomersarebeginningtoturntoorganicfarming.Organicfarmersalsousemanyothermethodstokeepthesoilfertile.Recently,however,scientistshavebeenfindingthatlong-termuseofthesefertilizerscancausedamagetothelandandevenmoredangerous,topeopleshealth.Task2Putthefourparagraphsinorder.,B,C,DA,Task2FindthestructureofthepassageWhatsthefunction（功能）ofthefirstparagraph?

toexplainthetopictoanalysethetopictointroducethetopicWhichtwoparagraphscanbegroupedtogether?

Para2problemsPara3organicfarmingPara4organicfarmingmethodsWhatstherelationshipbetweenParagraph2andParagraph3&

4?

Para2Chemicalfarmingcausestheproblems.Para3&

4Organicfarmingsolvestheproblems.,Para1TopicWhyarechemicalfertilizerssopopularinfarming?

.agreatwaytostopcropdiseaseandincreaseproduction.,Para2Problems,1.,2.,Howmanyproblemsarelistedinthisparagraph?

Problemscausedbychemicalfertilizers,First,Also,3.Inaddition,Watercropsanimals,humans,Damagetheland,Fruit,vegetables,otherfood,Para3&

4Solution,Task1Whatdoorganicfarmersfocuson?

Theyfocusonkeepingtheirsoilrichandfreeof,disease.,Para3&

4Solution,Task2Underline,theorganicfarming,methods,andtheir,advantages,inPara3&

4.,Task3Retelltheorganicfarmingmethodswiththehelpofthekeyinfo