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美联英语提供新概念英语文章及译文1两分钟做个小测试,看看你的英语水平 Statistics 统计学 Thereweretwowidelydivergentinfluen__sontheearlydevelopmentofstatisticalmethods.Statisticshadamotherwhowasdedicatedtokeepingorderlyrecordsofgover__entalunitsstatesandstatisticscomefromthesameLatinrootstatusandagentle__nlygamblingfatherwhoreliedon__the__ticstoincreasehisskillatplayingtheoddsingamesofchan__.Theinfluen__ofthemotherontheoffspringstatisticsisrepresentedbycountingmeasuringdescribingtabulatingorderingandthetakingof__nsuses-allofwhichledtomoderndescriptivestatistics.Fromtheinfluen__ofthefathercamemoderninferentialstatisticswhichisbasedsquarelyontheoriesofprobability. 统计方法的早期发展受到两种截然不同的影响统计学有一个“母亲”,她致力于井井有条地记录__机构的文件国家和统计学这两个词源于同一个拉丁语词根,status,还有一个有绅士般的赌博“父亲”,他依靠数学来提高赌技,以便在几率的游戏中取胜“母亲”对其子女统计学的影响表现在计数、测量、描述、制表、归类和人口普查所有这些导致了现代描述统计学的诞生由于“父亲”的影响则产生了完全基于概率论原理的现代推理统计学 Descriptivestatisticsinvolvestabulatingdepictinganddescribingcollectionsofdata.Thesedata__ybequantitativesuchasmeasuresofheightin____igen__orgradelevel--variablesthatarecharacterizedbyanunderlyingcontinuum--orthedata__yrepresentqualitativevariablessuchas___college__jororpersonalitytype.Large__ssesofdatamustgenerallyundergoapro__ssofsum__rizationorreductionbeforetheyarecomprehensible.Descriptivestatisticsisatoolfordescribingorsum__rizingorreducingtocomprehensibleformthepropertiesofanotherwiseunwieldy__ssofdata. 描述统计学涉及对所收集数据的制表、制图和描述这些数据可以是数量性的数据,如高度、智商、或者是层级性的数据——具有连续性的变量——或数据也可以代表性质变量,如性别、大学专业或性格类型等等数量庞大的数据通常必须经过概括或删减的程序才能为人所理解描述统计学____一个工具,它对极其庞杂的数据进行描述、概括或删减,使其变成能为人理解的东西 Inferentialstatisticsisafor__lizedbodyofmethodsforsolvinganotherclassofproblemsthatpresentgreatdifficultiesfortheunaidedhu__nmind.Thisgeneralclassofproblemscharacteristicallyinvolveattemptsto__kepredictionsusingasampleofobservations.Forexampleaschoolsuperintendentwishestodeterminetheproportionofchildreninalargeschoolsystemwhocometoschoolwithoutbreakfasth__ebeenvaccinatedforfluorwhatever.H__ingalittleknowledgeofstatisticsthesuperintendentwouldknowthatitisunne__ssaryandinefficienttoquestioneachchild:theproportionfortheentiredistrictcouldbeesti__tedfairlyaccuratelyfromasampleofasfewas100children.Thusthepurposeofinferentialstatisticsistopredictoresti__techaracteristicsofapopulationfromaknowledgeofthecharacteristicsofonlyasampleofthepopulation. 推理统计学是一套已定形了的方法体系,它解决的是光凭人脑极难解决的另一类问题这类问题的显著特点是试图通过取样调查来作出预测例如,有一位教育督察想知道在一个庞大的学校系统中,不吃早饭就上学的学生、已经做过防感冒免疫的学生,或其它任何类型的学生占多大比例若具备一些统计学的知识,这位督察应明白,询问每个孩子是没有必要而且没有效率的,只要用100个孩子为样本,他就可以相当精确地得出这些孩子占整个学区的比例了因此,推理统计学的目的就是通过了解一个群体中一些样本的特性,从而对整个群体的特性进行推测和估算 新概念英语文章及译文2 Coal-firedpowerplants 火力发电厂 Theinventionoftheincandes__ntlightbulbbyTho__sA.Edisonin1879createdade__ndforacheapreadily__ailablefuelwithwhichtogeneratelargeamountsofelectricpower.Coalseemedtofitthebillanditfueledtheearliestpowerstationswhichweresetupattheendofthenineteenth__nturybyEdisonhimself.Asmorepowerplantswereconstructedthroughoutthecountrytherelian__oncoalincreased.Sin__theFirstWorldWarcoal-firedpowerplantsh__eaccountedforabouthalfoftheelectricityprodu__dintheUnitedStateseachyear. 托马斯·爱迪生1879年发明的白炽灯导致对便宜、易得、可生产大量电能的燃料的需求煤似乎符合这个要求,并成为第一批电厂的燃料正是爱迪生本人在19世纪末建造了第一批电厂全国到处兴建电厂时,对煤的依赖加深了自第一次世界大战以来,美国每年约有一半的电力是以煤为燃料的电厂提供的 In1986suchplantshadacombinedgeneratingcapacityof2__000megawattsandconsumed83per__ntofthenearly900milliontonsofcoalminedinthecountrythatyear.Giventheun__rtaintyinthefuturegrowthofnuclearpowerandinthesupplyofoilandnaturalgascoal-firedpowerplantscouldwellprovideupto70per__ntoftheelectricpowerintheUnitedStatesbytheendofthe__ntury. 1986年这些电厂的总发电能力达到28900千瓦并且消耗了当年全国开采的九亿吨煤的83%考虑到核能发展以及石油、天然气供应中的不确定因素,到本世纪末,火力发电厂仍可能为美国提供多达70%的电力 Yetinspiteofthefactthatcoalhaslongbeenasour__ofelectricityand__yre__inonefor__nyyearscoalrepresentsabout80per__ntofUnitedStatesfossil-fuelreservesithasactuallyneverbeenthemostdesirablefossilfuelforpowerplants.Coalcontainslessenergyperunitofweightthannaturalgasoroil;itisdifficulttotransportanditisassociatedwithahostofenviro__entalissuesamongthemacidrain.Sin__thelate1960sproblemsofemissioncontrolandwastedisposalh__esharplyredu__dtheappealofcoal-firedpowerplants.Thecostofamelioratingtheseenviro__entalproblemsalongwiththerisingcostofbuildingafacilityaslargeandcomplexasacoal-firedpowerplanth__ealso__desuchplantslessattractivefromapurelyeconomicperspective. 然而,尽管煤__以来一直是电力的原料之一并且可能会继续如此煤占美国化石燃料储量的80%,它却不是电厂的理想燃料煤的单位能量含量低于石油和天然气,而且会导致包括酸雨在内的一系列环境问题从_____以来,排放控制和垃圾处理的问题极大地削弱了燃煤电厂的魅力由于减轻这些环境问题需要大量资金,而且建造庞大复杂的燃煤电厂的费用不断上涨,也使得这些电厂从经济角度上不具备吸引力 Changesinthetechnologicalbaseofcoal-firedpowerplantscouldrestoretheirattractivenesshowever.Whereassomeofthesechangesareevolutionaryandareintended__inlytoincreasetheproductivityofexistingplantscompletelynewtechnologiesforburningcoalcleanlyarealsobeingdeveloped. 改变火力发电厂的基础技术却可能恢复它们的吸引力虽然某些技术改进是渐进的,其目的只是提高现有电厂的生产率,但人们正在__全新的清洁燃煤的技术 新概念英语文章及译文3 ObtainingFreshwaterfromi__bergs 从冰山中获取淡水 Thecon__ptofobtainingfreshwaterfromi__bergsthataretowedtopopulatedareasandaridregionsoftheworldwason__treatedasajokemoreappropriatetocartoonsthanreallife.Butnowitisbeingconsideredquiteseriouslyby__nynationsespeciallysin__scientistsh__ewarnedthatthehu__nra__willoutgrowitsfreshwatersupplyfasterthanitrunsoutoffood. 把冰山拖到世界上人口稠密的地区和干旱地带,再从中获取淡水,这个想法曾一度被认为是一个笑话,更适合于卡通画,而非现实生活然而现在,许多国家正相当认真地考虑这件事情,特别是在科学家们发出警告之后科学家们认为人类将在耗尽粮食之前首先耗尽淡水资源 Glaciersareapossiblesour__offreshwaterthathasbeenoverlookeduntilre__ntly.Three-quartersoftheEarthsfreshwatersupplyisstilltiedupinglaciali__areservoirofuntappedfreshwatersoimmensethatitcouldsustainalltheriversoftheworldfor1000years.Floatingontheo__anseveryyearare7659trillio__etrictonsofi__encasedin_____i__bergsthatbreakawayfromthepolari__capsmorethanninetyper__ntofthemfromAntarctica.Hugeglaciersthatstretchovertheshallowcontinentalshelfgivebirthtoi__bergsthroughouttheyear. 冰川是一个直到最近以前一直被忽视的可能的淡水源全球四分之三的淡水还锁在冰川的冰块中冰川就是一个蓄水池,其中未__的淡水量是如此巨大,足够支持全世界的江河1000年每年有7659万亿公吨冰漂流在海洋中它们包含在10000座从极地冰帽中断裂出来的冰山中这些冰山的90%以上来自南极一年四季里,覆盖在浅层大陆架上的巨大冰川生成了众多冰山 I__bergsarenotlikeseai__whichisformedwhentheseaitselffreezesrathertheyareformedentirelyonlandbreakingoffwhenglaciersspreadoverthesea.Astheydriftawayfromthepolarregioni__bergssometimesmovemysteriouslyinadirectionoppositetothewindpulledbysubsu_____currents.Becausetheymeltmoreslowlythan__allerpie__sofi__i__bergsh__ebeenknowntodriftasfarnorthas35degreessouthoftheequatorintheAtlanticO__an.Tocorralthemandsteerthemtopartsoftheworldwheretheyareneededwouldnotbetoodifficult.Thedifficultyarisesinothertechnical__tterssuchasthepreventionofrapidmeltinginwarmercli__tesandthefunnelingoffreshwatertoshoreingreatvolume.Butevenifthei__bergslosthalfoftheirvolumeintowingthewatertheycouldprovidewouldbefarcheaperthanthatprodu__dbydesalinizationorremovingsaltfromwater.冰山和海水的冰不同,后者是海水自身结冰形成的,而冰山则完全是在陆地上形成的当冰川伸展到海水中时,冰山就断裂下来当漂离极地地区时,冰山有时会在底层洋流的推动下颇为神秘地逆风__由于冰山比小块的冰融化要慢,因此有的冰山在大西洋中向北飘到了赤道以南35°的地方把冰山蓄拦起来并拖到世界上需要它们的地方将不会太困难有困难的是其它的技术事宜比如,如何防止冰山在较暖的气候中迅速融化以及如何把大量的淡水收集到岸上去但是,即便在拖的过程中冰山失去了一半体积,这样做也远比从海水中脱盐取得淡水便宜两分钟做个小测试,看看你的英语水平。