網GMAT頻道小編第臨時間為列位考生整頓了2015年3/4月GMAT瀏覽部門機經，以供門生們參考!
1. 溫室氣體甲烷Methane【考古待確認】
【原始】——GMAT
V1一種溫室氣體M。曩昔以為是化石燃料，人，動物發生。
厥後發明植物也發生M。
海底的沉積物在冰河時代有過一次暴發，致使溫室氣體增長。(有一道關於冰河世紀的題，狗主讀文章的時刻把這段給漏了，應當謎底便是海底溫室氣體在冰河時代有一次大暴發)
樹木發生溫室氣體M，然則接收另一種溫室氣體二氧化碳。要辦理環球變暖題目，基本方法是削減化石燃料的焚燒。
V2.
P1. 似乎曩昔JJ見過，說甲烷methane 在大氣層裏，致使溫室效應, 甲烷來自於動物的甚麽，來自於combustion, 另有一個sources
P2. 說實在另有一個source很使人surprising，來自於plant的感化，以是研討發明雨林上方的甲烷密度會很高，並且這個plant發生甲烷正好說明了冰川裏的氣泡，是以溫度升高冰川熔化 會加重溫室效應。
然則遷移轉變說實在植物在削減，並且植物能接收另外一種溫室氣體二氧化碳，以是削減植物並非減緩溫室效應的方法。
背面似乎另有兩段，不到一屏半，然則文章比擬簡略，題目也還好
有一題問植物削減會怎樣，然後我選了甲烷削減，感到不太對，沒看到其他比擬像的選項
【考古】
V1. 1P說甲烷和二氧化碳同樣是一種溫室氣體;也會造成global warming。枚舉了造成大氣中M物資增長的緣故原由，如焚燒石化燃料等。fuel fossil burn, fire and other.(有題考這段的感化，我以為是供給配景材料)
2P “Surprisingly”(遷移轉變)科學家發明植物plant也會開釋M，提出如衛星空照的證據，說熱帶地域由於有較麋集的森林tropical forest，以是大氣中的M特殊會合。The article listed two studys to demonstrate that the plants really emit the methane.
3P (有些處所沒讀通) 持續說這一發明可以用於說明ice age先後甲烷的變更;仿佛是說植物開釋M也能夠說明陳腐的冰塊中的氣泡浬為什麽也有M…植物排放M的究竟也說明了另外一個科學謎題，即為何陳腐的冰層
取樣中有吝嗇泡含有S(又一個不熟悉的單詞)。。。。多是說跟著冰河入到海洋，海底也沉積了許多M，上一個冰河時代的停止大概便是這些貯存在海底的M被開釋的成果。然則證據表現海底也許四萬年都沒有激烈更改，以是這個應當不是致使冰河期停止的緣故原由。推想應當是植物大批的繁衍，開釋出M,致使均勻氣溫愈來愈高才使得冰河期停止。
4P 固然植物會開釋M，然則願望藉由削減植物來阻攔溫室效應仍舊是紕謬的，然則環球變暖是弗成逆的，還得有植物。由於植物可以接收別的更多的溫室氣體。想要和緩溫室效應照樣應當從削減石化質料fuel.的應用動手。(這段無考點)
V2. 第一段先先容了一下Methane是致使溫室效應的一種氣體，它可以起源於許多處所，好比焚燒化石，等等等等，個中一種是起源於植物。
第二段就證實，植物確切發生Methane.熱帶雨林上空一樣平常就會有Methane雲團。
第三段說，Methane還可以說明海底怎樣怎樣的(其時就沒怎樣懂得這句話= =)。海底假如甚麽甚麽多，那末就會開釋Methane.海地那甚麽甚麽的開釋與汗青異常相符，ice age就比擬少開釋Methane, warm time就比擬多開釋Methane。然則，曩昔的幾百年裏，海底並無忽然開釋大批Methane(以是溫室效應不完滿是海底的緣故原由)
第四段說，植物是會開釋Methane，然則咱們不克不及為了削減溫室效應就去削減植物。更有用的辦法是削減焚燒化石。
V3. 【疑似原文，待確認】
Most people know methane (often written as the chemical formula CH4) as natural gas. Approximately 600 million metric tons of it—both anthropogenic (from human activities) and natural—rise into the atmosphere every year. Wetlands such as swamps, marshes and rice paddies provide the greatest share. Cattle, sheep and termites also make methane, as a by-product of anaerobic microbial digestion in their gut. Forest and savanna fires release methane, as does the combustion of fossil fuels. Over the years, researchers have gained considerable knowledge about the global methane cycle, and the consensus of the Intergovernmental Panel on Climate Change (IPCC) in 2001 was that the major sources had probably been identified (although the proportion each source contributes was still uncertain).
In 2005 the scientists’ satellite measurements revealed “clouds” of methane over tropical forests. In light of our findings, however, their work made sense: green vegetation was the source of the methane clouds. Our findings would explain a trend that has puzzled climate scientists for years: fluctuations in methane levels in parallel with changes in global temperatures. Ice cores serve as natural archives that store information about atmospheric composition and climate variability going back almost a million years. Tiny bubbles of air trapped in the ice reveal the relative concentrations of atmospheric gases in the past. We see in the ice cores, for example, that variations of past carbon dioxide levels are closely linked to changes in global temperatures. During ice ages, carbon dioxide concentrations are low; during warm spells, levels increase. Another explanation that has been suggested involves the gas in a form known as methane hydrates. These develop at high pressure, such as that found on the ocean floor. An unknown but possibly very large quantity of methane is trapped in this form in ocean sediments. The sudden release of large volumes of methane from these sediments into the atmosphere has been suggested as a possible cause for rapid global warming events in the earth’s distant past. Yet recent results from polar ice core studies show that marine methane hydrates were stable at least over the past 40,000 years, indicating that they were not involved in the abrupt increases of atmospheric methane during the last glacial cycle. We know that terrestrial vegetation is very sensitive to environmental changes, and thus the total amount of vegetation on the planet varies as the climate cools down and warms up during glacial cycles. In light of our findings, such variations should now be seriously considered as a possible cause of declines in methane levels during glacial periods and rises during the interglacials.
Our discovery also led to intense speculation that methane emissions by plants could diminish or even outweigh the carbon storage effect of reforestation programs. But our calculations show that the climatic benefits gained by establishing new forests to absorb carbon dioxide would far exceed the relatively small negative effect of adding more methane to the atmosphere (which may reduce the overall carbon uptake of the trees by 4 percent at most). The potential for reducing global warming by planting trees is most definitely positive. A more legitimate concern is whether the methane produced by vegetation can have an impact on climate in the near future. Although plants are not responsible for the massive increase of methane in the atmosphere since preindustrial times, they do tend to grow faster. As we can expect methane emissions from vegetation to increase with temperature, this would lead to even more warming. This vicious cycle would be a natural phenomenon except for its speed, which is accelerated mainly by anthropogenic activities such as burning fossil fuels. The large plant feedback to global climate change that most likely happened in the past, however, is probably unlikely today because so many forests have been cut down. The problem is not the plants; it is the global large-scale burning of fossil fuels.
【段落大意】
P1：先容甲烷，甲烷是致使溫室效應的一種氣體，甲烷發生的門路。
P2：[遷移轉變]科學家發明植物也會開釋甲烷，並研討發明了雨林上方的大氣中甲烷濃度較大。這個發明大概可以解釋植物排放的甲烷與環球升溫有關。
P3：對冰層舉行研討，由於留在冰層中的微吝嗇泡中的氛圍能揭露曩昔大氣氣體的相對於濃度，而這又對甲烷與氣象幹系的研討供給贊助。
P4：固然植物會開釋甲烷，然則願望經由過程削減植物來阻攔溫室效應弗成行，要緩解溫室效應照樣應從削減石化燃料的應用動手。
市場價：HK$ 92
