新概念第四冊課文翻譯及學習筆記 Lesson20全套

新概念第四冊課文翻譯及學習筆記：Lesson20【課文】Firstlistenandthenanswerthefollowingquestion.聽錄音，然后回答以下問題。Whatarethetwodifferentwaysinwhichsnakepoisonacts?Howitcameaboutthatsnakesmanufacturedpoisonisamystery.Overtheperiodstheirsaliva,amild,digestivejuicelikeourown,wasconvertedintoapoisonthatdefiesanalysiseventoday.Itwasnotforceduponthembythesurvivalcompetition;theycouldhavecaughtandlivedonpreywithoutusingpoison,justasthethousandsofnon-poisonoussnakesstilldo.Poisontoasnakeismerelyaluxury;itenablesittogetitsfoodwithverylittleeffort,nomoreeffortthanonebite.Andwhyonlysnakes?Cats,forinstance,wouldbegreatlyhelped;norunningfightswithlarge,fierceratsortussleswithgrownrabbits--justabiteandnomoreeffortneeded.Infact,itwouldbeanassistancetoallcarnivoresthoughitwouldbeatwo-edgedweaponwhentheyfoughteachother.But,ofthevertebrates,unpredictableNatureselectedonlysnakes(andonelizard).OnewondersalsowhyNature,withsomesnakes,concoctedpoisonofsuchextremepotency.Intheconversionofsalivaintopoison,onemightsupposethatafixedprocesstookplace.Itdidnot;somesnakesmanufactureapoisondifferentineveryrespectfromthatofothers,asdifferentasarsenicisfromstrychnine,andhavingdifferenteffects.Onepoisonactsonthenerves,theotherontheblood.Themakersofthenervepoisonincludethemambasandthecobrasandtheirvenomiscalledneurotoxic.Vipers(adders)andrattlesnakesmanufacturethebloodpoison,whichisknownashaemolytic.Bothpoisonsareunpleasant,butbyfarthemoreunpleasantisthebloodpoison.Itissaidthatthenervepoisonisthemoreprimitiveofthetwo,thatthebloodpoisonis,sotospeak,anewerproductfromanimprovedformula.Bethatasitmay,thenervepoisondoesitsbusinesswithmanfarmorequicklythanthebloodpoison.This,however,meansnothing.Snakesdidnotacquiretheirpoisonforuseagainstmanbutforuseagainstpreysuchasratsandmice,andtheeffectsontheseofviperinepoisonisalmostimmediate.JOHNCROMPTONThesnake【Newwordsandexpressions生詞和短語】salivan.唾液digestiveadj.助消化的defyv.使不可能analysisn.分析preyn.被捕食的動物fierceadj.兇猛的tusslen.扭打carnivoren.食肉動物vertebraten.脊椎動物lizardn.蜥蜴concoctv.調制potencyn.效力conversionn.轉變arsenicn.砒霜strychninen.馬錢子堿mamban.樹眼鏡蛇cobran.眼鏡蛇venomn.毒液neurotoxicadj.毒害神經(jīng)的vipern.蝰蛇addern.蝮蛇rattlesnaken.響尾蛇haemolyticadj.溶血性的viperineadj.毒蛇【課文注釋】1.Howitcameaboutthatsnakes...amystery.這句話的主語是一個句子：Howitcameaboutthatsnakesmanufacturedpoison，謂語部分是isamystery。主語從句中的it是形式主語，真正主語是thatsnakesmanufacturedpoison，因為主語太長，所以使用it作先行主語的結構。2.overtheperiods，經(jīng)過很長時間。例句：Overtheperoids,shefinallymanagedtowalkoutofthebreaking-upshadowwhichhadbroughtmuchpaintoher.經(jīng)過很長時間，她終于走出了那段曾給她帶去無數(shù)傷痛的分手陰影。3.convertinto，改變成。Ifonethingisconvertedorconvertsintoanother,itischangedintoadifferentform.例句：Thesolarcellcanconverttheenergyofsunlightintoelectricenergy.太陽能電池能把陽光的能量轉化為電能。4.liveon，靠……生活。關于live的短語在第9課：王室諜報活動中有講過哦，可以去復習一下^^戳我去復習>>5.atwo-edgedweapon，一把雙刃刀，這里的意思是：如果食肉動物都有毒液，就會造成食肉動物之間的互相殘殺。雙刃劍、雙刃刀，也可以說成double-edgedsword:asituationordecisionthathasbothpositiveandnegativeaspects例句：Scientificdevelopmentmaybeatwo-edgedweapon,ononehanditliftspeople'slivingstandard,ontheotherhanditposespotentialthreatstotheenvironment.科技進步是一把雙刃劍，一方面它提高了人們的生活水平，另一方面也對環(huán)境構成了潛在威脅。6.acton，對……起作用;遵照。①Ifaforceorsubstanceactsonsomeoneorsomething,ithasacertaineffectonthem.有作用。例句：Thesemedicalherbsaresaidtoactontheheart.據(jù)說這些藥草對心臟起作用。②Ifyouactonadviceorinformation,youdowhathasbeenadvisedorsuggested.遵照。例句：Apatientwillusuallylistentothedoctor'sadviceandactonit.通常病人都會聽從并遵照醫(yī)生的建議去做。7.byfarthemoreunpleasant，更難受得多，byfar是“……得多”的意思。例句：Itisquickerbyfartogobytrain.乘火車要快得多。8.sotospeak，插入語，有“可以這樣說”，“打個比方說”的意思。9.Bethatasitmay，這是一個倒裝的讓步狀語從句，相當于howeverthatmaybe，可譯成“盡管如此”。10.doesitsbusinesswithman，在人的身上發(fā)揮作用，要人的命。11.theeffectsontheseofviperinepoison，these是指ratsandmice，介詞賓語結構ofviperinepoison是作effets的定語?！緟⒖甲g文】蛇是怎樣產(chǎn)生毒液的，這是一個謎。蛇的唾液本來和我們?nèi)说南阂粯尤岷?，但?jīng)過漫長的時間，演變成了今天仍無法分析清楚的毒液。毒液不是生存競爭強加給它們的，它們也可以不用毒液捕捉動物而生存，就像今天成千上萬的無毒蛇那樣。毒液對毒蛇來說只不過是一種舒適生存的優(yōu)越手段，它使蛇不用費多大力氣就能捕獲到食物，輕咬一口即可。為什么只有蛇才有毒液呢?譬如說，如果貓有毒液，那對貓會大有幫助，它就不必再和又大又兇的老鼠邊跑邊博斗了，也不必再和大兔子扭斗了，只要咬一口，就不必再費大力氣。因此，任何食肉動物有了毒液，都能從中獲益。不過，當它們相互撕打時，毒液就成了利弊參半的武，可以殺死對方，也可以被對方的毒液殺死。然而，在脊椎動物中，大自然神秘模測地只選擇了蛇(還有一種蜥蜴)，人們弄不清楚大自然為什么在某些蛇的身上調制出如此高效的毒液來。人們可能認為，唾液轉變成毒液，其中有固定的程序。其實沒有。有些蛇產(chǎn)生的毒液在各方面與另外一些毒蛇產(chǎn)生的毒液不相同，就像砒霜不同于馬錢子堿一樣。