公共英语等级考试复习指导四级阅读题.docx

公共英语等级考试复习指导四级阅读题公共英语等级考试复习指导四级阅读题天才就是百分之九十九的汗水加百分之一的'灵感。以下是小编为大家搜索整理的公共英语等级考试复习指导四级阅读题，希望对正在关注的您有所帮助!更多精彩内容请及时关注我们应届毕业生考试网!Sustainabledevelopmentisappliedtojustabouteverythingfromenergytocleanwaterandeconomicgrowth,andasaresultithasbecomedifficulttoquestioneitherthebasicassumptionsbehinditorthewaytheconceptisputtouse.Thisisespeciallytrueinagriculture,wheresustainabledevelopmentisoftentakenasthesolemeasureofprogresswithoutaproperappreciationofhistoricalandculturalperspectives.Tostartwith,itisimportanttorememberthatthenatureofagriculturehaschangedmarkedlythroughouthistory,andwillcontinuetodoso.medievalagricultureinnorthernEuropefed,clothedandshelteredapredominantlyruralsocietywithamuchlowerpopulationdensitythanitistoday.Ithadminimaleffectonbiodiversity,andanypollutionitcausedwastypicallylocalized.Intermsofenergyuseandthenutrientscapturedintheproductitwasrelativelyinefficient.Contrastthiswithfarmingsincethestartoftheindustrialrevolution.Competitionfromoverseasledfarmerstospecializeandincreaseyields.Throughoutthisperiodfoodbecamecheaper,safeandmorereliable.However,thesechangeshavealsoledtohabitat(栖息地)lossandtodiminishingbiodiversity.What’smore,demandforanimalproductsindevelopingcountriesisgrowingsofastthatmeetingitwillrequireanextra300milliontonsofgrainayearby2050.yetthegrowthofcitiesandindustryisreducingtheamountofwateravailableforagricultureinmanyregions.Allthismeansthatagricultureinthe21stcenturywillhavetobeverydifferentfromhowitwasinthe20th.thiswillrequireradicalthinking.Forexample,weneedtomoveawayfromtheideathattraditionalpracticesareinevitablymoresustainablethannewones.Wealsoneedtoabandonthenotionthatagriculturecanbe“zeroimpact”.Thekeywillbetoabandontherathersimpleandstaticmeasuresofsustainability,whichcentreontheneedtomaintainproductionwithoutincreasingdamage.Insteadweneedamoredynamicinterpretation,onethatlooksattheprosandcons(正反两方面)ofallthevariouswaylandisused.Therearemanydifferentwaystomeasureagriculturalperformancebesidesfoodyield:energyuse,