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Unit8PopularScienceLesson22(E—C)Oil(1)ByG..C.ThornleyTherearethreemaingroupsofoil:animal,vegetableandmineral.Greatquantitiesofanimaloilcomefromwhales,thoseenormouscreaturesoftheseawhicharethelargestremaininganimalsintheworld.ToprotectthewhalefromthecoldoftheArcticseas,naturehasprovideditwithatickcoveringoffatcalledblubber.Whenthewhaleiskilled,theblubberisstrippedoffandboileddown,eitheronboardshiporonshore.Itproducesagreatquantityofoilwhichcanbemadeintofoodforhumanconsumption.Afewothercreaturesyieldoil,butnonesomuchasthewhale.Theliversofthecodandthehalibut,twokindsoffish,yieldnourishingoil.Bothcodliveroilandhalibutliveroilaregiventosickchildrenandotherinvalidswhoneedcertainvitamins.Theseoilsmaybeboughtatanychemist’s.Vegetableoilhasbeenknownfromantiquity.Nohouseholdcangetonwithoutit,foritisusedincooking.Perfumesmaybemadefromtheoilsofcertainflowers.Socpaaremadefromvegetableandanimaloils.Totheordinaryman,onekindofoilmaybeasimportantasanother.Butwhenthepoliticianortheengineerreferstooil,healmostalwaysmeansmineraloil,theoilthatdrivestanks,aeroplanesandwarships,motor-carsanddiesellocomotivs,theoilthatisusedtolubricateallkindsofmachinery.Thisistheoilthatisusedtolubricateallknidsofmachinery.Thisistheoilthathaschangedthelifeofthecommonman.Whenitisrefinedintopetrolitisusedtodrivetheinternalcombustionengine.Toitweowetheexistenceofthemotor-car,whichhasreplacedtheprivatecarriagedrawnbythehorse.Toitweowethepossibilityofflying.Ithaschangedthehorse.Toitweowethepossiblilityofflying.Ithaschangedthemethodsofwarfareonlandandsea.Thisknidofoilcomesoutoftheearth.Becauseitburnswell,itisusedasfuelandinsomewaysitissuperiortocoalinthisrepect.Manybigshipsnowburnoilinsteadofcoal.Becauseitburnsbrightly,itisusedforillumination;countlesshomesarestillilluminatedwithoil-burninglamps.Becauseitisveryslippery,itisusedforlubrication.Twometalsurfacesrubbingtogethercausefrictionandheat;butiftheyareseparatedbyathinfilmofoil,thefrictionandheatarereduced.Nomachinewouldworkforlongifitwerenotproperlylubricated.Theoilusedforthispurposemustbeofthecorrectthickness;ifitistoothinitwillnotgivesufficientlubrication,andifitistoothickitwillnotreachallpartsthatmustelubricated.(fromEnglishThroughReading)参考译文：G.C.索恩利油可以分为三大类：动物油、植物油、矿物油。大量的动物油是从鲸鱼身上得来的。鲸鱼是海里的庞然大物，是世界上现有动物中最大的一种。大自然为了保护鲸鱼，使它不不致在北冰洋受冻，便让它长了厚厚的一层脂肪，叫做鲸脂。鲸鱼杀死之后，把鲸脂剥下来熬油，这项工作有的是在船上进行的，有的是在岸上进行的。这样，就能生产出大量的油，供人们食用。有些动物也出油，但都没有鲸鱼出得多。鳕鱼和比目鱼，这两种鱼的肝脏出的油营养丰富。从这两种鱼得来的鱼肝油可以给缺少某种维生素的患儿或其他病人服用。这两种鱼肝油在任何一家药房里都可以买到。植物油自古以来就为人们所熟悉。任何家庭都离不开它，因为做饭的时候就要用它。有些花儿产生的油可以用来制造香水。植物油和动物油还可以用来制作肥皂。对一般人来说，这种油或那种油可能都是重要的。但是当政治家或工程师谈到油的时候，他所指的几乎总是矿物油。这种油可以用来开坦克，开飞机，开军舰，开汽车，开柴油机车，可以用来润滑各种机械。就是这种油改变了普通人的生活。这种油经过提炼变成汽油以后，可以用来开动内燃机。就是因为有了这种油，我们才有可能飞行。它还改变了陆战和海战的方法。这种油来源于地下。因为它易于燃烧，可以用作燃料，而且在这方面比煤还有若干优越之处。现在许多大轮船就烧油而不烧煤。因为它燃烧时非常明亮，也可以用来照明，许多家庭现在仍靠没灯照明。因为它非常滑润，可以用作润滑剂。两个金属面相擦，就要产生摩擦和热；但如果在它们之间抹上薄薄的一层油，就可以减少摩擦，降低热度。任何机械如果不使用一定的润滑剂，就不能持续工作。润滑油的浓度必须适当，太稀则起不到应有的润滑作用，太稠则流不到所有需要润滑的零件。Lesson23(E—C)TheOtherRoad(1)ByRachelCarsonWestandnowwheretworoadsdiverge.ButunliketheroadsinRobertFrost’sfamiliarpoem,theyarenotequallyfair.Theroadwehavelongbeentravelingisdeceptivelyeasy,asmoothsuperhigh-wayonwhichweprogresswithgreatspeed,butatitsendliesdisaster.Theotherforkoftheroad—theone“lesstraveledby”—offersourlast,ouronlychancetoreachadestinationthatassuresthepreservationofourearth.Thechoice,afterall,isourstomake.If,havingenduredmuch,wehaveatlastassertedour“righttoknow”,andif,knowing,wehaveconcludedthatwearebeingaskedtotakesenselessandfrighteningrisks,thenweshouldnolongeracceptthecounselofthosewhotelluswemustfillourworldwithpoisonouschemicals;weshouldlookaboutandseewhatothercourseisopentous.Atrulyextraordinaryvarityofalternativestothechemicalcontrolofinsectsisavailable.Somearealreadyinuseandhaveachievedbrilliantsuccess.Othersareinthestageoflaboratorytesting.Stillothersarelittlemorethanideasinthemindsofimaginativescientists,waitingfortheopportunitytoputthemtothetest.Allhavethisincommon:theyarebiologicalsolutions,basedonunderstandingofthelivingorganismstheyseektocontrol,andofthewholefabricoflifetowhichtheseorgai\nismsbelong.Specialistsrepresentingvariousareasofthevastfieldofbiologyarecontributing—entomologists,pathologists,geneticists,physiologists,biochemists,ecologists—allpouringtheirknowledgeandtheircreativeinspirationsintotheformationofanewscienceofbioticcontrols.“Anysciencemaybelikenedtoariver,”saysaJohnsHopkinsbiologist,ProfessorCarlP.Swanson.“Ithasitsobscureandunpretentiousbeginning;;itsquietstretchesaswellasitsrapids;itsperiodsofdroughtaswellasoffullness.Itgathersmomentumwiththeworkofmanyinvestinagatorsandasitisfedbyotherstreamsofthought;itisdeepenedandbroadenedbytheconceptsandgeneralizaationsthataregraduallyevolved.”Soitiswiththescienceofbiologicalcontrolinitsmodernsense.Inamericaithaditsobscurebeginningsacenturyagowiththefirstattemptstointroducenaturalenemiesofinsectsthatwereprovingtroublesometofarmers,aneffortthatsometimesmovedslowlyornotatall,butnowandagaingatheredspeedandmomentumundertheimpetusofanoutstandingsuccess.Ithaditsperiodofdroughtwhenw