朗文英语听说教程1-Unit-2听力原文

Unit2HewKindsofFoodPart1Teacher:Hi,everybody…how'sitgoing?...Good.…Haseveryoneturnedintheirhomework?Allrighty,thenlet'sgetstarted.IFyouremember,lastweekwewerediscussingsomeresearchintheareaofgenetics.Today,I'dliketotalkaboutsomethingI'msureyou'veallheardabout-geneticallymodifiedorGMfood.Geneticallymodifiedfoodisfood--eitheraplantoranimal--thathasbeenalteredinthelaboratorybyscientists.Thescientiststakesomethingfromoneplantoranimal,andaddittoadifferentplantoranimaltomakeitgrowinadifferentway.Today,we'lllookatsomeofthebenefits,andthepossiblerisksofgeneticallymodifiedfond.Let'sstartwithadiscussionofsomeofthebenefitsofGMfood.Geneticscientistsarereallytryingtomakefoodplantsthatarebetterthannormalplants,tomakeplantsthatarealteredinwaysthatmaketheplantgrowbetterortastebetterorbehealthiertoeatthannormalplants.Onebenefitisthatgeneticallymodifiedplantsmayneedfewerpesticidesthannormalplants.Forexample,thereisatypeofcornthatisbadforinsects--whentheinsectseatthecornplant,theydie.However,thecorndoesn'thurtpeople.Thistypeofcornisbeneficialbecausefarmersusefewerpesticidestogrowthecorn,andsothereislesspollutionintheenvironment.Alsothecornislessexpensivebecausethefarmersdon'thavetospendalotofmoneyonpesticides.So,byusingfewerpesticides,thecornischeaperandtheenvironmentiscleaner.Anotherbenefitofgeneticallymodifiedplantsisthattheymaygrowbetterthannormalplants.Oneexampleisatypeofgeneticallymodifiedstrawberrythatcangrowincoldweather.Thesearebetterthannormalstrawberriesbecausefarmerscanplantthestrawberriesearlierinthespringandlaterinthefall,whennormalstrawberriesusuallydie.So,asaresult,farmerscangrowmanymorestrawberriesthantheyusedto.Sothat'sanotherbenefitplantsthatgrowbetter.Finally,athirdbenefitisthatmanygeneticallymodifiedplantsstayfreshlongeraftertheyareharvested.So,forexample,thereisalandoftomatothatstaysfreshinthestoreforabouttwomonths,insteadofoneortwoweeks.Thismeansthatthereismoretimetogetthefoodtothestoresandthatstoreshavemorerimetosellthefood.Lessfoodisthrownawayandwasted.Soit'sagreatbenefittohavefoodthatstaysfreshlonger--andwecanconsumemoreofthefoodwegrow.Part2Teacher:Nowthatwe'velookedatsomeofthebenefitofgeneticallymodifiedplants,let'stalkabouttherisksofgrowingthistypeoffood.Wedon'treallyknowwhattheharmfuleffectsare,butthereareseveralthingsthatpeopleateworriedabout.Oneriskisthatthegeneticallymodifiedplantsmaystarttodominatetheotherwildplantsintheenvironment.Thisisaproblemwithsometypesoftomatoes,forexample.Thenewtomatoplantsarestrongerthannormalplants,andbecausetheyarestrongerandgrowfasterthanthewildplants,thegeneticallymodifiedtomatoesmaystarttodominatetheenvironment,causingthewildplantstodie.Sohavingoneplantdominatealltheotherplantsisn’ttgoodfortheenvironment.Anotherriskisthatgeneticallymodifiedplantswillhurtwildanimalsandinsectsintheenvironment.Forexample,thegeneticallymodifiedcorn1mentionedearlierhasalreadycausedthisproblem.Nowsomebutterfliesthatlivenearthecornaredying--butterfliesthataregoodinsects,anddon'teatthecorn.It'spossiblethatcorniskillingthebutterfliessomehow,butwe'renotsure.Wejustknowthatmorebutterfliesaredyingthannormal.Butclearlythere'sariskthatgeneticallymodifiedfoodscanhurtanimalsandinsectsintheenvironment.Butprobablythemostimportantriskisthatgeneticallymodifiedfoodmaybeharmfultothepeoplewhoconsumethefood.Thealterationsintheplantsmaycauseseriousproblemsforpeople--wejustdon'tknow.Scientistsaretryingallkindsofnewthings,suchasputtingthegenesfromanimalsintoaplant.Forexample,tomakeafruitlikestrawberriesstayfreshlonger,scientiststookagenefromafish--agenethathelpsthefishliveincoldwaterandputthatintoastrawberry.Willthatstrawberrybeharmfultopeople?Wedon'tknow.Buritmaybe.Soit'sclearthattherearesomeimportantbenefitstogeneticallymodifiedfoodbutalsosomerisks-risksthatalotofpeoplearen'twillingtotake.Solet'sstophereanddiscussanyquestionsyouhaveatthispoint…1.Whatisgeneticallymodifiedfood?a.Freshfoodb.Dangerousfoodc.Alteredfood2.Whatgeneticallymodifiedfruitdidthespeakermention?a.Strawberriesb.Applesc.Bananas3.Whatisabenefitofgeneticallymodifiedfood?a.Itneedsfewerpesticides.b.Itgrowsinlessspace.c.Itdominatestheenvironment.4.Whatisariskofgeneticallymodifiedfood?a.Itmaystayfreshlonger.b.Itmaybemoreexpensive.c.Itmaybeharmfultopeople.5.Whatarethreebenefitsofgeneticallymodifiedfood?Geneticallymodifiedfoodneedsfewerpesticides.Geneticallymodifiedfood/plantsgrowbetterthannormal.Inaddition,theystayfreshlongeraftertheyareharvested.6.Whatarethreerisksofgeneticallymodifiedfood?Geneticallymodifiedfood/plantsmaydominateotherplantsintheenvironment.Also,theymighthurtwildanimalsandinsects.Theymightevenhurtthepeoplewhoeatthem.