托福阅读tpo68R-3原文+译文+题目+答案+背景知识
1
TPO68 阅读-3 Research into Aging and Extending Life Span
原文+译文+题目+答案+背景知识
原文
Research into Aging and Extending Life Span
①The mounting evidence for age genes that influence the aging process is by no
means conclusive , but it is quite impressive, coming from a variety of independent
research from aging in worms and fruit flies to antioxidants and gene repair
mechanisms, and human mutations. Still, the connections are circumstantial.
②Christopher Wills, professor of biology at the University of California in San
Diego, thinks that by 2025 science will likely isolate the mammalian age genes in
mice. We share roughly 75 percent of our genes with mice and have much the
same body chemistry; this is a strong reason to believe that an age gene found in
mice could also be at work in humans. If such genes are located, the next step
would be to find out if these age genes have their counterparts in humans. Wills
believes that if they are found in humans, they may extend the human life span
perhaps to 150 years.
③But by 2020, when personalized DNA sequencing becomes widespread, a
second tactic may prove fruitful as well. By analyzing populations of healthy
individuals in their nineties and beyond, scientists will find it possible to use
computers to compare their genetic backgrounds and cross-check for similarities in
key genes that are suspected of influencing aging. A combination of studies on the
DNA of long-lived animals and on the personalized DNA sequences of elderly
individuals may considerably narrow down the search for the age gene.
④As yet, none of these methods can prove that we can increase the human life
span. Indeed, the only theory with a proven track record of extending the life span
of animals is the caloric restriction theory, which states that animals which
consume calories just above starvation levels live significantly longer than the
average. Although this theory flies in the face of common sense (a well-fed animal 2 is well nourished and healthy, and should have greater resistance to disease and
aging), it has held up under repeated testing among a wide range of animals.
Scientists have consistently increased the life span of rats and mice in the
laboratory by 50 to 100 percent. It is the only laboratory-tested theory of age
extension for animals that has held up under decades of careful scrutiny. Why?
⑤Across the animal kingdom, the life span of animals is roughly inversely
correlated to the metabolism rate. The slower their normal metabolism rate, the
longer their normal life span. In 1996, in a study that reduced the calorie intake of
200 monkeys by 30 percent, the monkeys were shown to have a slower
metabolism rate, a longer life span, and reduced rates of cancer, heart disease, and
diabetes. “We have known for 70 years that if you feed laboratory mice less food,
they age slower, they live longer, and they get diseases less frequently. We find
that monkeys respond in the same way as rodents and that the same biological
changes may be in play here,” says George Roth of the National Institute of Aging.
⑥There is still room for scientific debate on the question “why?” Ron Hart, a
scientist at the National Center for Toxicological Research, believes that the answer
may tie in the high body temperature of mammals, and humans in particular.
“Heat causes pieces of the DNA molecule to split off randomly, and it must be
repaired,” Hart says. “Under calorie restriction, though, the engine runs cooler
and there’s less damage. Merely reducing caloric intake by 40 percent reduced
this form of spontaneous DNA damage almost 24 percent!” Furthermore, at a
higher internal body temperature, oxygen is being burned at a greater rate,
creating more free radicals, which also speed up the aging process. Cooling the
body, on the other hand, increases the amount of antioxidants in the body. Hart
found a fourfold increase in the enzyme catalase and a threefold increase in
superoxide dismutase in animals on a restricted diet. “What’s fascinating," Hart
concludes, “is that reduced food intake is the only experimental paradigm ever
found that enhances DNA repair.” Hart is so convinced of the importance of this
work that in 1993 he began the first systematic studies of caloric restrictions in
humans.
译文
研究老化和延长寿命 3 ①虽然越来越多的关于影响衰老过程的衰老基因都不具结论性，但却令人印象深刻，这些证据来自各种独立的研究，从蠕虫和果蝇的衰老到抗氧化剂和基因修复机制，以及人类突变。尽管如此，这些联系还是间接的。
②加州大学圣地亚哥分校的生物学教授克里斯托弗·威尔斯认为，到2025年，科学可能会分离出老鼠体内的哺乳动物衰老基因。我们和老鼠大约有75%的基因相同，身体化学成分也基本相同;这是一个有力的理由让我们相信在老鼠身上发现的衰老基因可能也在人类身上起作用。如果找到了这些基因，下一步将是找出这些衰老基因在人类中是否有对应的基因。威尔斯相信，如果在人类身上发现它们，它们可能会将人类寿命延长到150岁。
③但到2020年，当个性化DNA排序变得普遍时，第二种策略可能也会被证明是富有成效的。通过分析90岁以上的健康人群，科学家们将发现有可能使用计算机来比较他们的遗传背景，并交叉检查被怀疑会影响衰老的关键基因的相似性。对长寿动物DNA和老年人个性化DNA序列的研究进行结合，可能会大大缩小对衰老基因的搜索范围。
托福阅读tpo69R-1原文+译文+题目+答案+背景知识
TPO69阅读-1WhySnakesHaveForkedTongues原文...............................................................1译文...............................................................3题目...............................................................4答案...............................................................8背景知识...........................................................9
原文WhySnakesHaveForkedTongues
①Theforkedtongueofsnakeshasintriguedpeopleformillennia,inspiringmanyhypotheses.Inmanyculturesandreligions,theforkedtonguesymbolizesmalevolenceanddeceit.ThefirstpersonknowntoinquireaboutthefunctionalsignificanceoftheforkedtonguewasAristotle;hesuggestedthatitwoulddoublethepleasureofsensationsoftaste.Bythebeginningofthetwentiethcentury,theconsensuswasthatthesnake’stongueisatactileorgan;thatis,thesnakeusesittotapthegroundmuchasablindpersonusesacane.
托福阅读tpo56R-3原文+译文+题目+答案+背景知识
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TPO56 阅读-3 Conditions on Early Earth and the Beginnings of Life
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托福阅读tpo40R-3原文+译文+题目+答案+背景知识
托福阅读
tpo40
R-3
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原文
Amphibian
Thermoregulation
①
In
contrast
to
mammals
and
birds,
amphibians
are
unable
to
produce
thermal
energy
through
their
metabolic
activity,
which
would
allow
them
to
regulate
their
body
temperature
independent
of
the
surrounding
or
ambient
temperature.
However,
the
idea
that
amphibians
have
no
control
whatsoever
over
their
body
temperature
has
been
proven
false
because
their
body
temperature
does
not
always
correspond
to
the
surrounding
temperature.
While
amphibians
are
poor
thermoregulators,
they
do
exercise
control
over
their
body
temperature
to
a
limited
degree.
②
Physiological
adaptations
can
assist
amphibians
in
colonizing
habitats
where
extreme
conditions
prevail.
The
tolerance
range
in
body
temperature
represents
the
range
of
temperatures
within
which
a
species
can
survive.
One
species
of
North
American
newt
is
still
active
when
temperatures
drop
to
-2
°
C
while
one
South
American
frog
feels
托福阅读tpo46R-3 原文+译文+题目+答案+背景知识
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托福tpo46r-3 Ecosystem Diversity and Stability
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原文
Ecosystem Diversity and Stability
托福阅读第三篇tpo75R -3原文+译文+题目+答案+背景知识
托福阅读第三篇tpo75R-3原文+译文+题目+答案+背景知识原文......................................................................................................1译文......................................................................................................4题目......................................................................................................7答案....................................................................................................13背景知识............................................................................................14
原文SeismicWaves
①Seismicwaves-energywavesproducedbyearthquakes-permitscientiststodeterminethelocation,thickness,andpropertiesofEarth'sinternalzones.Theyaregeneratedwhenrockmassesaresuddenlydisturbed,suchaswhentheybreakorrupture.Vibrationsspreadoutinalldirectionsfromthesourceofthedisturbance,travelingatdifferentspeedsthroughpartsofEarth'scrustandinteriorthatdifferinchemicalcompositionandphysicalproperties.Theprincipalcategoriesofthesewavesareprimary,secondary,andsurface.Allthreetypesofwavesarerecordedonaninstrumentcalledaseismograph.②Primarywaves,orP-waves,arethespeediestofthethreekindsofwavesandthereforethefirsttoarriveataseismographstationaftertherehasbeenanearthquake.TheytravelthroughtheuppercrustofEarthatspeedsof4to5kilometerspersecond,butnearthebaseofthecrusttheyspeedalongat6or7kilometerspersecond.Intheseprimarywaves,pulsesofenergyaretransmittedasasuccessionofcompressionsandexpansionsthatparallelthedirectionofpropagationofthewaveitself.Thus,agivensegmentofrocksetinmotionduringanearthquakeisdrivenintoitsneighborandbouncesback.Theneighborstrikesthenextparticleandreboundsandsubsequentparticlescontinuethemotion.Vibrationalenergyisanaccordion-likepush-pullmovementthatcanbetransmittedthroughsolids,liquidsandgases.Ofcourse,thespeedofPwavetransmissionwilldifferinmaterialsofdifferentdensityandelasticproperties.
tpo67三篇托福阅读TOEFL原文译文题目答案背景知识
tpo67三篇托福阅读TOEFL原文译文题目答案背景知识阅读-1.....................................................................................2原文...................................................................................2译文...................................................................................5题目...................................................................................8答案.................................................................................16背景知识..........................................................................17阅读-2...................................................................................21原文.................................................................................21译文.................................................................................25题目.................................................................................27答案.................................................................................34背景知识..........................................................................35阅读-3...................................................................................39原文.................................................................................40译文.................................................................................43题目.................................................................................46答案.................................................................................53背景知识..........................................................................54阅读-1原文CropEngineering①Ourcurrentabilitytopreciselyengineercropgenomeswasprecededbyalonghistoryofgeneticmanipulationinagriculture.Humanimpactanditsaccompanyingeffectsbeganearlyinourhistoryatmanytropicalandsubtropicalsitesaroundtheglobe.Ourancestorswereomnivores,consumingwhateverplantoranimalmaterialtheyfortuitouslyencountered.Eventhen,humanshadconsiderableeffectsontheenvironment,reducingandevendrivingtoextinctionpopulationsoftheanimalspeciestheyhuntedandexpandingthedistributionofplantsbyaccidentallydistributingseedsastheymigrated.
托福阅读tpo63R-2原文+译文+题目+答案+背景知识
TPO63阅读-2StructureandCompositionofComets
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原文
StructureandCompositionofComets
托福阅读tpo67R-2原文+译文+题目+答案+背景知识
TPO67
阅读-2
Human
Activity
and
the
Archaeological
Record
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原文
Human
Activity
and
the
Archaeological
Record
①
Archaeologists
distinguish
the
“
cultural
”
formation
processes
of
the
archaeological
record
(those
involving
some
kind
of
human
activity)
托福阅读tpo57R-3原文+译文+题目+答案+背景知识
托福阅读tpo57R-3TheProblemofNarrativeClarityinSilentFilms原文.....................................................................................................................................................1译文.....................................................................................................................................................2题目.....................................................................................................................................................3答案.....................................................................................................................................................7背景知识.............................................................................................................................................8原文TheProblemofNarrativeClarityinSilentFilms①Beginningin1904,Americancommercialfilmmakingbecameincreasinglyorientedtowardstorytelling.Moreover,withthenewemphasisonone-reelfilms,narrativesbecamelongerandnecessitatedaseriesofcamerashots.Filmmakersfacedthechallengeofmakingstoryfilmsthatwouldbecomprehensibletoaudiences.Howcouldtechniquesofediting,camerawork,acting,andlightingbecombinedsoastoclarifywhatwashappeninginafilm?Howcouldthespectatorgraspwhereandwhentheactionwasoccurring?②Overthespanofseveralyears,filmmakerssolvedsuchproblems.Sometimestheyinfluencedeachother,whileatothertimestwofilmmakersmighthappenonthesametechniqueindependently.Somedevicesweretriedandabandoned.By1917,filmmakershadworkedoutasystemofformalprinciplesthatwerestandardinAmericanfilmmaking.ThatsystemhascometobecalledtheclassicalHollywoodcinema.Despitethatname,manyofthebasicprinciplesofthesystemwerebeingworkedoutbeforefilmmakingwascenteredinHollywood,and,indeed,manyofthoseprincipleswerefirsttriedinothercountries.IntheyearsbeforetheFirstWorldWar,filmstylewasstilllargelyinternational,sincefilmscirculatedwidelyoutsidetheircountryoforigin.③Thebasicproblemthatconfrontedfilmmakersearlyinthesilent-movieerawasthataudiencescouldnotunderstandthecausal,spatial,andtemporalrelationsinmanyfilms.Iftheeditingabruptlychangedlocales,thespectatormightnotgraspwherethenewactionwasoccurring.Anactor’selaboratepantomimemightfailtoconveythemeaningofacrucialaction.Areviewofa1906filmlaysouttheproblem:“Regardlessofthefactthatthereareanumberofgoodmotionpicturesbroughtout,itistruethattherearesomewhich,althoughphotographicallygood,arepoorbecausethemanufacturer,beingfamiliarwiththepictureandtheplot,doesnottakeintoconsiderationthatthefilmwasnotmadeforhimbutfortheaudience.Amovierecentlyseenwasverygoodphotographically,butthestorycouldnotbeunderstoodbytheaudience.”Inafewtheaters,alecturermightexplaintheplotasthefilmunrolled,butproducerscouldnotrelyonsuchaids.④Filmmakerscametoassumethatafilmshouldguidethespectator’sattention,makingeveryaspectofthestoryonthescreenasclearaspossible.Inparticular,filmsincreasinglysetupachainofnarrativecausesandeffects.Oneeventwouldplainlyleadtoaneffect,whichwouldinturncauseanothereffect,andsoon.Moreover,aneventwastypicallycausedbyacharacter’icalchasesorbriefmelodramasdependedmoreonphysicalactionorfamiliarsituationsthanoncharactertraits.Increasinglyafter1907,however,characterpsychologymotivatedactions.Byfollowingaseriesofcharacters’goalsandresultingconflicts,thespectatorcouldcomprehendtheaction.⑤Everyaspectofthesilent-filmstylecametobeusedtoenhancenarrativeclarity.Stagingorframingactionindepthcouldshowthespatialrelationshipsamongelements.Intertitleswrittentextsappearingperiodicallythroughoutasilentmovietoexplaintheactioncouldaddnarrativeinformationbeyondwhattheimagesconveyed.Closerviewsoftheactorscouldsuggesttheiremotionsmoreprecisely.Color,setdesign,andlightingcouldimplytimeofday,themilieuoftheaction,andsoon.⑥Someofthemostimportantinnovationsofthisperiodinvolvedthewaysinwhichcamerashotswereputtogether,oredited,tocreateastory.Inonesense,editingwasaboontothefilmmaker,permittinginstantmovementfromonespacetoanotherorcutstocloserviewstorevealdetails.Butifthespectatorcouldnotkeeptrackofthetemporalorspatialrelationsbetweenoneshotandthenext,editingmightalsoleadtoconfusion.Insomecases,intertitlescouldhelp.Editingalsocametoemphasizecontinuityamongshots.Certainvisualcuesindicatedthattimewasflowinguninterruptedlyacrosscuts.Betweenscenes,othercuesmightsuggesthowmuchtimehadbeenskippedover.Whenacutmovedfromonespacetoanother,thedirectorfoundwaystoorienttheviewer.译文无声电影中的叙事清晰度问题①自1904年起，美国的商业电影制作越来越倾向于讲故事。而且，随着对单卷电影的强调，叙事变得更长，也就需要进行一系列的拍摄。电影制作人面临的挑战是制作出观众能够理解的故事电影。如何将剪辑、摄影、表演和灯光等技术结合起来，去阐明电影中正在发生的事情?观众如何理解动作发生的时间以及地点?②在过去几年的时间里，电影制作人将这些问题解决了。有时他们相互影响，而在一些时候，两个电影制作人可能独立研发了同一个技术。一些设备被尝试后被放弃。到1917年，电影制片人已经制定出一套正式的原则体系，它也成为了美国电影制作的标准。这一体系被称为“经典好莱坞电影”。尽管有这个名字，在电影制作以好莱坞为中心之前，这个体系的许多基本原则就已经制定出来了，而且实际上其中许多原则首先是在其他国家试行的。在第一次世界大战之前的几年里，因为电影在它们的原籍国之外传播广泛，它们的风格在很大程度上仍然是国际化的。③在无声电影时代早期，电影制片人面临的一个基本问题是观众无法理解许多电影中的因果、空间和时间关系。如果编辑突然改变了地点，观众可能不知道新动作发生在哪里。演员精心制作的手势可能无法表达出关键动作的含义。一篇对1906年一部电影的评论揭示了这样一个问题:“尽管的确有很多好电影,但是一些拍摄很好的电影整体观感却很差,因为制片人熟悉电影画面和情节,没有考虑到这部电影不是为他而作，而是为观众而作。最近看的一部电影在摄影上很逼真，但故事情节却让观众看不懂。”在一些剧院，叙述者可能会在电影放映时解释情节，但制片人不能依赖这种辅助手段。④电影制片人开始认为电影应该引导观众的注意力，让故事的各个方面都尽可能清晰地展现在屏幕上。特别是，电影越来越多地建立起一系列叙事因果链。一件事显然会导致一种结果，而这种结果又会反过来引起另一种结果，如此循环。此外，事件往往是由角色的信仰或欲望引起的。人物心理在早期电影中并不是特别重要。滑稽的追逐或简短的情节剧更多地依赖于身体动作或熟悉的场景，而不是人物特征。然而，在1907年之后，人物心理逐渐成为行为的动机。通过一系列人物的目标和因此产生的冲突，观众可以理解动作。⑤无声电影风格的每一个方面都被用来提高叙事的清晰度。有深度的分阶段或成帧动作可以展示元素之间的空间关系。字幕可以在图像所传达的内容之外添加叙述信息。演员的近景镜头可以更准确地表明他们的情绪。色彩、布景设计和灯光可以暗示一天中的时间、动作的环境等等。⑥这一时期最重要的一些创新包括将镜头组合或编辑成故事的方式。从某种意义上说，剪辑对电影制作人来说是一种恩惠，允许它从一个空间迅速移动到另一个空间，或者将镜头切到更近的位置来揭示细节。但是，如果观众无法跟上一个镜头与下一个镜头之间的时间或空间联系，剪辑也可能导致混乱。在一些情况下，字幕可能会有所帮助。编剧也开始强调镜头之间的连贯性。某些视觉线索表明，时间不间断地在剪辑片段中流逝。在场景之间，其他线索可能会暗示有多少时间被跳过了。当剪辑片段从一个空间转移到另一个空间时，导演找到了引导观众的方法。题目
托福阅读tpo51R-3原文+译文+题目+答案+背景知识
TPO51
阅读-3Population
Growth
in
Nineteenth-Century
Europe
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Population