11月18日的托福考試已經(jīng)結(jié)束，那么當天的考試真題有哪些呢?如何解答這些真題呢?這似乎是很多出國人士比較感興趣的問題，和出國留學網(wǎng)一起來了解了解吧!下面是小編整理的閱讀真題相關(guān)資訊，歡迎閱讀。
    　　2017年11月18日托?？荚囬喿x真題最新解析
    　　閱讀部分考試回憶如下：
    　　1. Preventing Overgrowth among Tree Branches
    　　shedding剪枝的意義。一個是因為有些樹枝消耗掉的碳物質(zhì)比生產(chǎn)的多，另一個原因是有時候氣候很干，剪枝減少水的消耗。
    　　詞匯題補充：
    　　exposed = unprotected
    　　with no warning = without any indication beforehand
    　　congestion = overcrowding
    　　2. Crown of Thorns Starfish and Coral Reefs
    　　冠狀棘海星，話題重復2011.01.08
    　　珊瑚的消失和一種海星的數(shù)量猛增有關(guān)系，主要說的是導致猛增的原因(環(huán)境+人)
    　　詞匯題補充：
    　　outbreak = sudden increase
    　　accompany = occur along with
    　　converge = come together
    　　severity = seriousness
    　　原題重現(xiàn)：
    　　The crown of thorns starfish, Acanthaster Tlanci, is large, twenty-five to thirty-five centimeters in diameter, and has seven to twenty-one arms that are covered in spines. It feeds primarily on coral and is found from the Indian Ocean to the west coast of Central America, usually at quite low population densities. Since the mid-1950s, population outbreaks at densities four to six times greater than normal have occurred at the same time in places such as Hawaii, Tahiti, Panama, and the Great Barrier Reef. The result has often been the loss of a fifty percent to nearly one hundred percent of the coral cover over large areas.
    　　A single Acanthaster can consume five to six square meters of coral polyps per year, and dense populations can destroy up to six square kilometers per year and move on rapidly. Acanthasters show a preference for branching corals, especially Acroporids. After an outbreak in a particular area, it is common to find that Acroporids have been selectively removed, leaving a mosaic of living and dead corals. In places where Acroporids previously dominated the community devastation can be almost complete, and local areas of reefs have collapsed.
    　　Areas of dead coral are usually colonized rapidly by algae and often are later colonized by sponges and soft corals. Increases in abundance of plant-eating fish and decreases in abundance of coral-feeding fish accompany these changes. Coral larvae settle among the algae and eventually establish flourishing coral colonies. In ten to fifteen years the reefs often return to about the same percentage of coral cover as before. Development of a four-species diversity takes about twenty years.
    　　Two schools of thought exist concerning the cause of these outbreaks. One group holds that they are natural phenomena that have occurred many times in the past, citing old men's recollections of earlier outbreaks and evidence from traditional cultures. The other group maintains that recent human activities ranging from physical coral destruction through pollution to predator removal have triggered these events.
    　　One theory, the adult aggregation hypothesis, maintains that most species is more abundant than we realize when a storm destroys coral and causes a food shortage. The adult Acanthasters converge on remaining portions of healthy coral and feed hungrily. Certainly there have been outbreaks of Acanthaster following large storms, but there is little evidence that the storms have caused the enough reef damage to create a food shortage for these starfish.
    　　Two other hypotheses attempt to explain the increased abundance of Acanthaster after episodes of high terrestrial runoff following storms. The first hypothesis is that low salinity and high temperatures favor the survival of the starfish larvae. The second hypothesis emphasizes the food web aspect, suggesting that strong fresh water runoff brings additional nutrients to the coastal waters, stimulating phytoplankton production and promoting more rapid development and better survival of the starfish larvae.
    　　Those favoring anthropogenic (human influenced) causes have pointed to the large proportion of outbreaks that have been near centers of human populations. It has been suggested that coral polyps are the main predators of the starfish larvae. Destruction of coral by blasting and other bad land use practices would reduce predation on the starfish larvae and cause a feedback in which increases in Acanthaster populations cause still further coral destruction. Unfortunately, there are too few documented instances of physical destruction of coral being followed by outbreaks of Acanthaster for these hypotheses to be fully supported.
    　　Another group of hypothesis focuses on removal of Acanthaster's predators. Some have suggested that the predators might have been killed off by pollution whereas others have suggested that the harvesting of vertebrate and invertebrate predators of Acanthaster could have reduced mortality and caused increased abundance of adults. The problem with this group of hypothesis is that it is difficult to understand how reduced predation would lead to sudden increases in Acanthaster numbers in several places at the same time in specific years. It seems probable that there is no single explanation but that there are elements of the truth in several of the hypotheses. That is there are natural processes that have led to outbreaks in the past, but human impact has increased the frequency and severity of the outbreaks.
    　　3.Dorset Culture
    　　格林蘭島Dorset Culture的起源，首先是由于氣候變冷，一部分人遷走了，另一部分留下來的人創(chuàng)立了文明。這些人發(fā)明了工具來面對寒冷氣候，后來氣候變暖了，另一部落的人遷移過來消滅了這個文明。
    　　詞匯題補充：
    　　allowed for = made possible
    　　harsh = severe
    　　duration of sea ice = length of time the ice lasts
    　　annihilated = destroyed
    　　4.Changes in the Amount of Forest on the Great Plains
    　　舊題重復：2015年9月25日文章
    　　本篇屬于比較規(guī)律的一篇生物文章，從森林變化這種現(xiàn)象著手，進而分析背后的原因; 建議大家多多了解相關(guān)的背景知識，比如 TPO 09：The Arrival of Plant Life in Hawaii; TPO 25：The Evolutionary Origin of Plants，從這些文章中我們可以知道植物的產(chǎn)生和進化原理，并且之后背后的原因。每種植物的生長和進化套路相似，所以大家可以仔細分析一下這兩篇文章的結(jié)構(gòu)，總結(jié)類似的文章結(jié)構(gòu)規(guī)律和出題特征。
    　　文章內(nèi)容：最初被常綠林覆蓋的森林，由于氣候變得溫暖干燥，變成了落葉林，最后成了草地。在一些山脊之類的地方樹木比較占優(yōu)勢，一方面山頂氣候涼爽并且接收到更多的降水(precipitation)，另一方面，山脊是天然的防火地帶(natural firebreak)，但草原被燒毀后依舊能夠擁有“野火燒不盡”的勢頭 。然而在大平原地區(qū)，森林減少后，接下來又經(jīng)歷了逆襲，數(shù)量開始增多，具體的原因主要在于人類的活動，隨著農(nóng)牧業(yè)的發(fā)展，草原數(shù)量逐漸減少，火災頻率也隨之降低，所以，森林又得以回歸 。
    　　詞匯題補充：
    　　dense = thick
    　　eased into = slowly entered
    　　retain = keep
    　　inevitable = certain
    　　5.How Plants and Animals Arrived in the Hawaiian Islands
    　　舊題重復：2014年12月27日文章
    　　6. Early Modern Industrialization
    　　舊題重復：2017年3月11日文章
    　　詞匯題補充：
    　　determinants = causes
    　　hastened = rushed
    　　diffusion = dispersal
    　　perfected = completed
    　　7. Birds and Food Shortage
    　　舊題重復：2015年12月20日文章
    　　文章內(nèi)容：
    　　這篇是講鳥類儲存能量的。鳥類通過儲存食物或者脂肪來度過食物不充足的時期，但是這個只能緩解食物短缺，不能徹底解決這個問題。越小的鳥就越需要更多的能量來生長，儲存能量難度也更大，特別舉了一個例子是蜂鳥需要不停的進食：大的鳥儲存能量多，并且不需要消耗太多能量去生長，所以儲存的能量可以撐很長時間，但是大鳥有時候需要儲存能量來遷徙或者繁殖。還說了有一些鳥會通過降低新陳代謝速率來減少能量消耗，類似于一種哺乳動物冬眠的狀態(tài)，蜂鳥可能每天晚上都會這樣。
    　　詞匯題補充：
    　　duration of = length of
    　　enables = allows
    　　in some degree = to a certain extent
    　　8. 古埃及金字塔那些法老，對各個法老的記錄來研究埃及歷史
    　　9. 恐龍的討論
    　　10. 北極圈的居民
    　　11. 農(nóng)業(yè)變遷
    　　12. 植物的自我保護機制
    　　13. 昆蟲的一種群居行為
    　　14. 密西根和埃及的鄉(xiāng)村建設(shè)，一個分布均勻，一個分布緊密
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