GRE閱讀中的邏輯單題專門對(duì)學(xué)生的邏輯思維進(jìn)行直接考查，我們GRE老師對(duì)這種文章已經(jīng)給同學(xué)們做了比較多的介紹。但是這種邏輯單題卻不是最典型的GRE閱讀理解。GRE閱讀中最典型、或者說GRE最小的單元是短文章（shorter passage），一般不到200個(gè)單詞，后面跟兩道題。按照官方的說法，短文章一般relatively straightforward and less dense（相對(duì)不那么復(fù)雜難懂）。所以對(duì)考生來說，多練習(xí)短文章，才能打好基礎(chǔ)。今天我們就來看一篇2021年出現(xiàn)過的機(jī)經(jīng)短文章。
01
Because they accumulate in an ordered manner that records changes within a lake and its drainage basin, lake sediments are particularly valuable for reconstructing ancient climate conditions. Natural materials such as pollen grains, minerals, diatoms, and animal microfossils preserved in sediments can be used to infer past conditions as these materials are affected by environmental variables. Pollen grains composed of sporopollenin, for example, can be used to infer past vegetation shifts. Because both natural climate change and human agricultural practices can lead to changes in vegetation, however, differentiation of these effects using pollen alone is difficult. In many areas of Mesoamerica, for instance, changes in the relative abundance of pollen types after 1000 BC were highly influenced by human-induced land clearance.
1. The author mentions “sporopollenin” primarily in order to
A. suggest that the conclusion set forth in the preceding sentence is overly general
B. support, by means of an illustration, an assertion made in the preceding sentence
C. introduce a concept for which a more specific example is given in the following sentence
D. identify a possible reason for the problem that is described in the following sentence
E. give an example that appears to contradict a principle set forth in the preceding sentence
Consider each of the choices separately and select all that apply.
2. Which of the following does the passage present as a reason that lake sediments are of particular value in the reconstruction of ancient climate conditions?
A. They allow scientists to distinguish between naturally occurring and human-induced vegetation changes.
B. They contain natural materials that are relatively unaffected by environmental variables during accumulation.
C. They collect over time in an ordered fashion.
02
文章大意：
湖底的沉積物是以一種有秩序的方式累積的，這種方式可以記錄一個(gè)湖及其流域的歷史變化情況。所以，要想重構(gòu)古代氣候的各種情況，湖底沉積物提供的信息尤其有價(jià)值。一些保存在湖底沉淀物中的天然物質(zhì)，如花粉粒、礦物質(zhì)、硅藻、動(dòng)物的細(xì)微骸骨化石等，可以用來推斷過去的天氣狀況，因?yàn)檫@些物質(zhì)當(dāng)年曾經(jīng)受到過環(huán)境（氣候）變量的影響。比如，包含sporopollenin（孢子花粉素，請(qǐng)同學(xué)們注意，這種單詞不用背也不用學(xué)）成分的花粉粒，就可以被用來推測過去植被的變化情況。不過，因?yàn)樘鞖庾兓腿祟愞r(nóng)業(yè)活動(dòng)都會(huì)導(dǎo)致植被的變化，光用花粉這一種東西無法區(qū)分植被的變化到底是由天氣變化導(dǎo)致還是人類農(nóng)業(yè)活動(dòng)導(dǎo)致。在中美洲的很多地區(qū)，在公元前1000年至今，（湖底沉積物中）花粉種類的數(shù)量的變化，就在很大程度上受到了人類伐木平整出空地這種活動(dòng)的影響（不僅受氣候變化的影響）。
題目解析：
1、 作者提到sporopollenin，主要的修辭目的是……？
作者提到sporopollenin，是講包含sporopollenin成分的花粉粒，可以用來推測植被變化，進(jìn)而推測氣候變化情況。這是在用具體舉例的方式支持文章上一句話做出的一個(gè)斷言。文章上一句話說的是，一些天然物質(zhì)（如花粉粒、礦物質(zhì)、硅藻、動(dòng)物化石等），可以用來推斷過去的天氣狀況。這句話就具體說，花粉可以用來推斷過去的植被變化情況（進(jìn)而推斷過去的天氣變化狀況）。簡單地說，這句話是在illustrate上一句話。所以B選項(xiàng)正確。
2、 文章說，“要想重構(gòu)古代氣候的各種情況，湖底沉積物提供的信息尤其有價(jià)值”，文章提出的原因有哪些？
文章說了區(qū)別不出來天氣變化和人類活動(dòng)這兩種因素引起的變化，所以A選項(xiàng)錯(cuò)誤。B選項(xiàng)中說“unaffected by environmental variables”，而根據(jù)文章，正是因?yàn)楹壮练e物中的物質(zhì)會(huì)受到氣候條件的影響，它們才有用，有價(jià)值。所以B選項(xiàng)錯(cuò)誤。
C選項(xiàng)中的collect是不及物動(dòng)詞，意思和文章第一句話中的accumulate接近。C選項(xiàng)中的fashion的意思和文章第一句話中的manner接近。所以C選項(xiàng)They collect over time in an ordered fashion 就和文章第一句話中的They accumulate in an ordered manner基本是對(duì)應(yīng)的。所以C選項(xiàng)正確。
這篇文章到這里就講解完了但是還想提醒同學(xué)們?cè)贕RE的題庫里，一篇短文章可能有不只兩道題，而是有4道題。每次考試，短文章后面是跟著兩道題，但是不一定是哪兩道。在兩場考試中，文章是一樣的，出現(xiàn)的題目卻可能不一樣。在一場考試中，會(huì)出現(xiàn)其中兩道題；在另一場考試中，還是這篇文章，但出現(xiàn)的可能是另外兩道題。
比如今天講的這篇短文章，文章最后一句話，其實(shí)暗中表示了這樣一層意思：
根據(jù)中美洲的很多地區(qū)公元前1000年至今（湖底沉積物中）花粉種類的數(shù)量的變化，無法準(zhǔn)確推測公元前1000至今的氣候變化情況，因?yàn)閺墓?000年起，人類的某些活動(dòng)，也會(huì)影響花粉種類數(shù)量。
這最后一句話也是可以再出兩道題的。比如，可以出這樣一道問修辭目的的題目。
3. The author mentions “many areas of Mesoamerica” primarily in order to
A. suggest that the conclusion set forth in the preceding sentence is overly general
B. support, by means of an illustration, an assertion made in the preceding sentence
C. introduce a concept for which a more specific example is given in the following sentence
D. identify a possible reason for the problem that is described in the following sentence
E. give an example that appears to contradict a principle set forth in the preceding sentence
細(xì)心的同學(xué)一定注意到了。這道題的5個(gè)備選項(xiàng)和第1題一模一樣，但是題干問的不是sporopollenin了，而是問的文章最后一句話中的many areas of Mesoamerica。那答案選哪個(gè)呢？
本期答案：B
還可以出這樣一道推斷題目。
4. Which of the following statements regarding many areas of Mesoamerica can be inferred from the passage？
A. 根據(jù)中美洲的很多地區(qū)公元前1000年至今（湖底沉積物中）動(dòng)物化石的數(shù)量的變化，可以準(zhǔn)確推測公元前1000至今的氣候變化情況。
B. 中美洲很多地區(qū)公元前1000年至今（湖底沉積物中）花粉種類的數(shù)量的變化，受到人類活動(dòng)影響的嚴(yán)重程度，比受到氣候變化影響的嚴(yán)重程度，還要大。
C. 中美洲的很多地區(qū)公元前1000至今的湖底沉積物累積的方式，和其他地區(qū)不同。
D. 中美洲的很多地區(qū)公元前1000至今的氣候變化的模式，和其他地區(qū)不同。
E. 僅僅根據(jù)中美洲的很多地區(qū)公元前1000年至今（湖底沉積物中）花粉種類的數(shù)量的變化，無法準(zhǔn)確推測這些地區(qū)公元前1000至今的氣候變化情況。
本期答案：E
03
臨時(shí)返場：我們是2月12日寫完這篇文章，交付排版。非常碰巧的是，我們?cè)?月13日又得到了這篇文章的一道機(jī)經(jīng)新題。
5. The author refers to “Mesoamerica” in the passage primarily in order to
A. describe an instance in which scientists were unable to determine the cause of a past vegetation shift
B. question the claim that both natural climate change and human agricultural practices may be responsible for past vegetation shifts
C. provide an example to support the contention that pollen grains are highly resistant to decay
D. support the contention that pollen changes captured in sediments do not reliably indicate natural climate change
E. identify a possible weakness in the theory that natural materials can be useful in inferring past climatic conditions
本期答案：D
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