人教版必修4Unit2 Using language Reading 课件

Unit2Usinglanguage

ReadingChemicalororganicfarming?Wordspreview

chemicalproductionbacteriapestnutritionmineral

adj.化学的；关于化学的n.生产；制造n.细菌n.害虫；害兽；害鸟n.营养；滋养；食物n.矿物；矿石

discoveryfocussoilreduceroot

n.发现；发觉n.焦点；中心点vt.集中；聚焦n.土壤vt.减少；减缩n.根；根源Wordspreview

skimunderlinesummarycomment

vt.浏览；略读vt.画底线标出；强调n.总结；摘要；概要n.评论；议论vi.&vt.表达意见;

做出评论Wordspreview

Expressionspreview

buildupleadtofocusonkeep…freefrom/of逐渐增强;建立;开发导致;造成(后果)集中(注意力，精力等)于使…免受(影响，伤害等)；使…不含(有害物)

OrganicFarmingWhataregenetically-modifiedfoods?

ThetermGMfoodsorGMOs(genetically-modifiedorganisms)ismostcommonlyusedtorefertocropplantscreatedforhumanoranimalconsumptionusingthelatestmolecularbiologytechniques.WhataresomeoftheadvantagesofGMfoods?Theworldpopulationhastopped6billionpeopleandispredictedtodoubleinthenext50years.Ensuringanadequatefoodsupplyforthisboomingpopulationisgoingtobeamajorchallengeintheyearstocome.GMfoodspromisetomeetthisneedinanumberofways:Firstreading(3ms)Readthepassageonpage14,thenfindoutthemainideaofeachparagraph.Para1:Para2:Para3:Para4:Long-termuseoffertilizerscancausedamagetothelandandpeople‘shealth.Theproblemcausedbychemicalfertilizers.Somefarmersandmanycustomersarebeginningtoturntoorganicfarming.Organicfarmersalsousemanyothermethodstokeepthesoilfertile.Secondreading(5ms)Readthetextagainandanswerthefollowingquestions:1Whyarechemicalfertilizerssopopularinfarmingtoday?2Whatproblemscanbecausedbyusingchemicalfertilizers?3Whatisorganicfarming?4Whatisthemainreasonforusingorganicfarmingmethods?1.Whyarechemicalfertilizerssopopularinfarmingtoday?Theycanstopcropdiseaseandincreaseproduction.2Whatproblemscanbecausedbychemicalfertilizers?Therearethreeproblems.First,chemicalfertilizersaffectthesoilandthewatersupplybadly.Second,theyallowfarmerstogrowthesamecropyearafteryearandexhaustthesoil.Third,theykillbothhelpfulandharmfulpests.Organicfarmingissimplyfarmingwithoutusinganychemicals.3Whatisorganicfarming?4.Whatisthemainreasonforusingorganicfarmingmethods?Ahealthysoilreducesdiseaseandhelpscropsgrowstrongandhealthy.Thirdreading(8ms)Readthetextagain,andfillinthefollowingforms.MethodsoforganicfarmingAdvantagesofmethods1Farmersusenaturalwastefromanimals.1Thismakesthesoilricherinmineralsandsomorefertile.2Farmersoftenchangethekindofcropineachfieldeveryfewyears.2Changingthecropsrenewsthemineralsinthesoilandhelpsitbecomerichandhealthy.MethodsoforganicfarmingAdvantagesofmethods3Farmersplantcropswithdifferentlengthsofroots.3Thisusesdifferentlevelsofsoil.4Farmerssometimesplantgrassbetweencropsandleaveitintheground.4Thispreventswindorwaterfromcarryingawaysoilandactsasanaturalfertilizer.Whatisthedisadvantageofusingchemicalfertilizers?1.Leavingchemicalsinthegroundforalongtimeisnotgoodforthesoilorthewatersupply.2.Farmeroftengrowthesamecropyearafter.Asaresult,thesoilgetsexhausted.3.Chemicalfertilizerskillbothhelpfulandharmfulbacteriaandpests.Retelling(8ms)Retellthetextaccordingtothechart:OrganicfarmingI.Cropsgrowingwithnaturalfertilizers.II.Farmersprefernaturalwastefromanimals.NaturalfertilizerChemicalfertilizer1.make…richerandmorefertile2.reduce…andhelp…strong3.thefertilizerskill…andhealthy4.keepfree…fromchemicals1.leaving…isnotgood2.grow…yearafteryearIII.Farmerschangecropseverytwoorthreeyears.…tomakesurewhatisleft…Languagepoints1Thesechemicalsinthefoodsupply

buildupinpeople’sbodiesovertime.buildup

增强;建立；开发Hardworkingconditionsbuildupcharacter.艰苦的工作条件能磨练人的性格。

2Manyofthesechemicalscanleadtocancerorotherillnesses.leadto:导致；造成Toomuchworkandtoolittlerestoftenleadtoillness.

过量的工作和过少的休息会引起疾病。AllroadsleadtoRome.

条条大道通罗马。3Theyfocusonkeepingtheirsoilrichandfreeofdisease.focuson:集中(注意力，精力等）于Youshouldfocusyourattentiononyourwork.

把注意力集中在你的工作上。

Olympus:Focusonlife.

奥林巴斯：瞄准生活。4Thisalsokeepstheair,soil,waterandcropsfreefromchemicals.keeps…freefrom/of:使…免受（影响，伤害登）；使不含（有害物）keepfrom:

阻止;妨碍

Ihopeyouwillkeepfromdoinganythingrash.

我希望你不要做出任何鲁莽的事情来。

5Recently,however,scientistshavebeenfindingthatlong-termuseofthesefertilizerscancausedamagetothelandand,evenmoredangerous,topeople’shealth然而最近,科学家们发现长期使用化肥会给土地造成损害,甚至更危险的是会给人类的健康造成损害.1(1)however为副词,意为”然而，可是”，表转折，可用于句首,句末,句中,如在句中,起前后都要加逗号.例如:He,however,couldn’tpayfortheeducationthatyoungAlbertneeded.然而,他无法支付小艾伯特的教育费用(2)however为连词,引导让步状语从句,相当于nomatterhow,修饰形容词或副词.例如:Howeverhotitis,hewillnevertakeoffhiscoat.=Nomatterhowhotitis,hewillnevertakeoffhiscoat.无论多么热,他都不会把外套脱掉.Howeverfastyourun,youcan’tcatchupwitha