Petroleumis defined as agaseous,liquid, and semisolid naturally occurringsubstancethat consistschieflyof hydrocarbons (chemical compounds ofcarbonandhydrogen). Petroleumisthereforeatermthat includes both oil and natural gas. Petroleumis nearly always found inmarinesedimentaryrocks. In the ocean,microscopicphytoplankton(tiny floating plants) andbacteria(simple, single-celled organisms) are theprincipalsources oforganicmatter that is trapped and buried insediment. Most of theorganicmatter is buried inclaythat is slowly converted to afine-grainedsedimentaryrock known asshale. During thisconversion,organiccompounds are transformed to oil and natural gas.

Sampling on thecontinentalshelves and along the base of thecontinentalslopes has shown that fine mudsbeneaththe seafloorcontainup to 8 percentorganicmatter. Twoadditionalkinds ofevidencesupport thehypothesisthatpetroleumis a product of thedecompositionoforganicmatter: oil possessesopticalproperties known only in hydrocarbons derived fromorganicmatter, and oil containsnitrogenand certain compounds believed tooriginateonly in living matter. Acomplexsequenceof chemical reactions is involved in converting theoriginalsolidorganicmatter to oil and gas, andadditionalchemical changes mayoccurin the oil and gas even after they have formed.

It is now well established thatpetroleummigratesthroughaquifers and can become trapped in reservoirs. Petroleummigrationisanalogoustogroundwatermigration. When oil and gas are squeezed out of theshalein which they originated and enter a body of sandstone orlimestonesomewhere above, theymigratereadilybecause sandstones (consisting ofquartzgrains) and limestones (consisting ofcarbonateminerals) are much morepermeablethan anyshale. The force of molecular attraction between oil andquartzorcarbonateminerals is weaker than that between water andquartzorcarbonateminerals. Hence, because oil and water do not mix, water remains fastened to thequartzorcarbonategrains, while oil occupies the central parts of the larger openings in theporoussandstone orlimestone. Because oil is lighter than water, it tends toglideupward past the carbonate- and quartz-held water. In this way, oil becomes segregated from the water; when it encounters atrap, it can form a pool.

Most of thepetroleumthat forms in sediments does not find asuitabletrapandeventuallymakes its way, along withgroundwater, to the surface of the sea. It is estimated that no more than 0.1 percent of all theorganicmatter originally buried in asedimentiseventuallytrapped in an oil pool. It is not surprising,therefore, that the highestratioof oil and gas pools tovolumeofsedimentis found in rock no older than 2.5 million years - young enough so that little of thepetroleumhas leaked away - and that nearly 60 percent of all oil and gas discovered so far has been found instratathat formed in the last 65 million years This does not mean that older rocks produced lesspetroleum; itsimplymeans that oil in older rocks has had a longer time in which toleakaway.

How much oil is there in the world? This is an extremelycontroversialquestion. Many billions of barrels of oil have already been pumped out of the ground. A lot ofadditionaloil has been located by drilling but is still waiting to be pumped out. Possibly a greatdealmore oil remains to be found by drilling. Unlikecoal, thevolumeof which can be accurately estimated, thevolumeof undiscovered oil can only be guessed at. Guesses involve the use of accumulated experience from acenturyof drilling. Knowing how much oil has been found in an intensively drilled area, such as eastern Texas, experts make estimates of probable volumes in other regions where rock types and structures aresimilarto those in eastern Texas. Using thisapproachand considering all thesedimentarybasins of the world, expertsestimatethat somewhere between 1,500 and 3,000 billion barrels of oil willeventuallybe discovered.

Questions:
question_stem: According to paragraph 1, petroleum is formed in which of the following ways?
choices: tag: A
text: Bacteria and tiny plants undergo a change while they are buried in clay

tag: B
text: Carbon and hydrogen combine to form shale

tag: C
text: Ocean rocks are converted into organic compounds

tag: D
text: Oil and gas rise to the surface of sediment and are trapped in rocks
answer_key: A
explanation: 【题目翻译】根据第1段，石油是以以下哪种方式形成的？
A：细菌和微小植物埋在粘土中时会发生变化。
B：碳和氢结合形成页岩
C：海洋岩石被转化为有机化合物
D：油气上升到沉积物表面，被困在岩石中。

【判定题型】：题目问的是文章中的具体细节信息，故根据题目问法可以判断本题为事实信息题。

【关键词定位】：根据关键词“petroleum”,定位到 Passage 1 第4句，原句为“In the ocean, microscopic phytoplankton (tiny floating plants) and bacteria (simple, single-celled organisms) are the principal sources of organic matter that is trapped and buried in sediment. ”，意思是“在海洋中，微小的浮游植物（微小的漂浮植物）和细菌（简单的单细胞生物）是被留在或是埋在沉积物中的有机物的主要来源。”。

【逻辑分析】由定位句可知：微型浮游植物(微型浮游植物)和细菌(简单的单细胞生物)是有机物的主要来源。那么说明它们肯定会发生变化才会进一步变成有机物。

【选项分析】
A.与原文定位句意思相符，正确。
B.不是碳和氢结合就可以，文章也未直接提及。故错误。
C.大多数有机物都被埋在泥土里，泥土慢慢转化成一种细粒沉积岩，叫做页岩。在这个转化过程中，有机化合物转化为石油和天然气。所以并不是选项中的岩石被转化成有机化合物。故错误。
D.原文未提到油气上升，故错误。

question_stem: The word "trapped" in the passage is closest in meaning to
choices: tag: A
text: hidden

tag: B
text: destroyed

tag: C
text: caught

tag: D
text: found
answer_key: C
explanation: 【题目翻译】段落中的“trapped”一词最接近于
A 隐藏的
B 销毁
C 抓住
D 发现	

【判定题型】：题目要求选出与高亮单词意思最接近的选项，故判断本题为词汇题。

【关键词定位】：根据关键词“trapped”,定位到原句“In the ocean, microscopic phytoplankton (tiny floating plants) and bacteria (simple, single-celled organisms) are the principal sources of organic matter that is trapped and buried in sediment.”。

【词汇解析】：词汇“trapped”的意思是“诱捕；使…受限制，使…陷入困境”。带入到原句中，原句的意思是“在海洋中，微小的浮游植物（微小的漂浮植物）和细菌（简单的单细胞生物）是被捕获并埋藏在沉积物中的有机物质的主要来源。”。

【选项分析】
A 隐藏的。不符，错误
B 销毁。不符，错误
C 捕捉。同义替换，正确
D 发现。不符，错误

question_stem: All of the following are cited in paragraph 2 as evidence that petroleum is a product of the decomposition of organic matter EXCEPT
choices: tag: A
text: the amount of organic matter found in layers of mud below the seafloor

tag: B
text: the chemical changes that occur in oil and natural gas after they have formed

tag: C
text: the optical properties of oil

tag: D
text: the fact that oil contains nitrogen and other compounds believed to be of organic origin
answer_key: B
explanation: 【题目翻译】以下所有内容在第2段中均被引用为石油是有机物分解产物的证据，除非
A：在海底以下的泥层中发现的有机物量。
B：石油和天然气形成后发生的化学变化。
C：油的光学性质
D：石油中含有氮和其他有机化合物的事实

【判定题型】：根据题干中出现的大写“EXCEPT”/"NOT" 等其他明显表示否定的词，可以判定本题为否定事实信息题，需要找出与原文信息不符的那个答案。

【关键词定位】：根据题干关键词“the decomposition of organic matter”,可以将出题范围锁定在 Passage2 。

【选项分析】
A：选项对应文章第一句话，提到海底泥浆中含有高达8%的有机物，故 A 选项符合原文，排除。
B：选项在最后一句有提到，但是无关缠绕信息，所以 B 为正确答案。
C：第二句话说“two additional kinds of evidence”对应了 C 选项。排除。
D：原文 optical properties of oil 对应 D 选项：石油所含的氮和某些化合物，来源于有机物。故排除。

question_stem: According to paragraph 2, which of the following is true of the change of solid organic material into oil and gas?
choices: tag: A
text: It is more likely to occur along the base of continental slopes than on the continental shelves

tag: B
text: It only takes place in areas where the seafloor contains at least 8 percent organic matter

tag: C
text: It is a process that can be reversed through chemical changes that occur after the oil and gas have formed

tag: D
text: It involves a complicated series of chemical reactions
answer_key: D
explanation: 【题目翻译】根据第2段，以下哪一项是关于固体有机物质转化为油气的真实情况？
A：它更有可能发生在大陆斜坡的底部，而不是大陆架上。
B：它只发生在海底含有至少8%有机物的区域。
C：这是一个可以通过石油和天然气形成后发生的化学变化来逆转的过程。
D：这涉及一系列复杂的化学反应。

【判定题型】：题目问的是文章中的具体细节信息，故根据题目问法可以判断本题为事实信息题。

3、【关键词定位】：根据关键词“solid organic material”,定位到 Passage2 最后一句，原句为“A complex sequence of chemical reactions is involved in converting the original solid organic matter to oil and gas, and additional chemical changes may occur in the oil and gas even after they have formed.”。
意思是“将有机固体转化成石油和天然气涉及一系列复杂的化学反应，并且即使在石油和天然气形成之后可能还会发生其他的化学反应。”

【逻辑分析】原始的固体有机物质转化为石油和天然气这一过程中有很多化学反应。

【选项分析】
A.原文中未把2个地方相比较，故错误。
B.原文只是说：海底下面的细泥浆含有高达百分之八的有机物。并未说：只发生在海底含有至少8%有机物的区域。故错误。
C.原文未提及逆转。故错误。
D.与原文意思相符，定位句 complex sequence 对应选项 D 的 complicated series，因此正确答案为 D。

question_stem: Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.
choices: tag: A
text: When oil and gas are squeezed out of the rock in which they originated, it is probably because the layer of rock above them is much more permeable than shale

tag: B
text: Sandstones, which are made of quartz grains, and limestones, which are made of carbonate minerals, can hold much more oil and gas than any shale can

tag: C
text: When they are squeezed from the shale in which they were formed, oil and gas move easily into the much more permeable layers of sandstone or limestone above

tag: D
text: Oil and gas are squeezed out of sandstones, consisting of quartz grains, and migrate readily into limestones, which consist of carbonate minerals and are much more permeable
answer_key: C
explanation: 【题目翻译】下面哪句话最能表达文章中突出显示的句子中的基本信息？错误的选择会以重要的方式改变意义，或者遗漏重要的信息。
A：当石油和天然气从它们发源的岩石中被挤出时，可能是因为它们上面的岩层比页岩更具渗透性。
B：由石英颗粒制成的砂岩和由碳酸盐矿物制成的石灰石比任何页岩都能容纳更多的石油和天然气。
C：当它们从形成它们的页岩中被挤压出来时，油气很容易进入上面渗透性更强的砂岩或石灰岩层。
D：石油和天然气从由石英颗粒组成的砂岩中被挤压出来，很容易迁移到由碳酸盐矿物组成的、渗透性更强的石灰石中。

【判定题型】：根据题目问法，题目要求选择和高亮句意思逻辑都最为接近的句子，故判断本题为句子简化题。

【句子分析】When 引导从句，原句核心为：当它们被挤压时，油和气体能更轻易的移动至更易渗透的砂岩或石灰岩中去。

【选项分析】
A 缺少 migrate readily 此信息；错误
B 的 Sandstones 主语错误，不是原句核心；错误
C 的意思符合原句，故正确。
D 的 much more permeable 变为次要成分。错误

question_stem: Why does the author include the information that "The force of molecular attraction between oil and quartz or carbonate minerals is weaker than that between water and quartz or carbonate minerals"?
choices: tag: A
text: To help explain why petroleum behaves differently from water in bodies of sandstone and limestone

tag: B
text: To illustrate why petroleum migrates more rapidly through sandstone than it does through limestone

tag: C
text: To help explain how water and petroleum can mix in certain aquifers

tag: D
text: To account for the different molecular structures of oil and water
answer_key: A
explanation: 【题目翻译】为什么作者将“油与石英或碳酸盐矿物之间的分子引力弱于水与石英或碳酸盐矿物之间的分子引力”这一信息包括在内？
A：有助于解释为什么在砂岩和石灰岩中，石油的行为与水不同
B：为了说明为什么石油在砂岩中比在石灰岩中迁移更快。
C：有助于解释某些含水层中的水和石油是如何混合的。
D：说明油和水的不同分子结构

【判定题型】：根据题干问法“why …… include”，题目询问“xxxxxx”(文章引用内容)的修辞目的，可以判断本题为修辞目的题。

【关键词定位】：根据关键词“The force of molecular”,定位到 Passage 3 第4句，原句为“The force of molecular attraction between oil and quartz or carbonate minerals is weaker than that between water and quartz or carbonate minerals. ”。

【引用内容分析】定位句意思是：分子之间的吸引力在石油和石英、碳酸盐矿物之间是弱于水和石英、碳酸盐矿物的。
【选项分析】
Af 符合原文意思，正确。
B 选项的 more rapidly …than 未提及；错误
C 的 how…can mix 未提及；错误
D 的 account for…molecular structures 未提及。错误

question_stem: The word "encounters" in the passage is closest in meaning to
choices: tag: A
text: meets

tag: B
text: forms

tag: C
text: escapes

tag: D
text: avoids
answer_key: A
explanation: 【题目翻译】段落中的“encounters”一词最接近于
A：遇见
B：形成
C：逃亡
D：避免

【判定题型】：题目要求选出与高亮单词意思最接近的选项，故判断本题为词汇题。

【关键词定位】：根据关键词“encounters”,定位到原句“In this way, oil becomes segregated from the water; when it encounters a trap, it can form a pool.”。

【词汇解析】：词汇“encounters”的意思是“遭遇；邂逅”,带入到原句中，原句的意思是“这样，石油就与水分离开来；当遇到圈闭时就形成一个油藏。”。

【选项分析】
A：遇见。同义替换，正确
B：形成。不符，错误
C：逃亡。不符，错误
D：避免。不符，错误

question_stem: The word "suitable" in the passage is closest in meaning to
choices: tag: A
text: noticeable

tag: B
text: permanent

tag: C
text: protected

tag: D
text: appropriate
answer_key: D
explanation: 【题目翻译】段落中的“suitable”一词最接近于
A：显著的
B：永久的
C：保护的
D：合适的

【判定题型】：题目要求选出与高亮单词意思最接近的选项，故判断本题为词汇题。

【关键词定位】：根据关键词“suitable”,定位到原句“Most of the petroleum that forms in sediments does not find a suitable trap and eventually makes its way, along with groundwater, to the surface of the sea.”。

【词汇解析】：词汇“suitable”的意思是“合适的；适当的；相配的”,带入到原句中，原句的意思是“大多数形成于沉积物的石油都没有找到合适的圈闭，并最终通过某种方式随着地下水来到了海洋的表面。”

【选项分析】
A：显著的。不符，错误
B：永久的。不符，错误
C：保护的。不符，错误
D：合适的。同义替换，正确