GMAT阅读辅导 超详细答案解析

According to a recent theory(注意，提出最新理论，后一般展开理论具体内容), Archean-age gold-quartz vein systems were formed more than two billion years ago from magmatic fluids that originated from molten granite-like bodies deep beneath the surface of the Earth. //(第一层：介绍最新的关于太古代年龄黄金石英脉系统的形成理论)This theory is contrary to (与...相反)the widely held view (注意，提出被广泛认可的理论，后一般展开理论具体内容)that the systems were deposited from metamorphic fluids, that is, from fluids that formed during the dehydration of wet sedimentary tocks.(此句修饰metamorphic fluids，第一遍读文时可略读)//(第二层：介绍与最新理论相悖的被广泛认可的理论)

The recently developed theory has considerable practical importance(正评价词). Most of the gold deposits discovered during the original gold rushes were exposed at the Earth’s surface and were found because they had shed trails of alluvial gold that were easily traced by simple prospecting methods. Although(结构词，表让步)these same methods still lead to an occasional discovery, most deposits not yet discovered have gone undetected because they are buried and have no surface expression.//(第一层：最新理论的重大实践意义：最初发现金矿只需简单地根据砂金痕迹探测，而现在由于大多数金矿埋于地下，不易被发现)

The challenge in exploration is therefore(结构词，表因果联系) to unravel the subsurface geology of an area and pinpoint the position of buried minerals. Methods widely used today include(后提出三种现今使用的方法) (①analysis of aerial images that yield a broad geological overview;) ( ②geophysical techniques that provide data on the magnetic, electrical, and mineralogical properties of the rocks being investigated;) and (③sensitive chemical tests that are able to detect the subtle chemical halos that often envelop mineralization.)//(第一层：金矿勘测的难点以及目前广泛使用的三种探测方法)However( 结构词，表转折关系), none of these high-technology methods are of any value(负评价词)if the sites to which they are applied have never mineralized, and to maximize the chances of discovery the explorer must therefore(结构词，表因果) pay particular attention to selecting the ground formations most likely to be mineralized. //(第二层：如果勘察的地点从来没有矿化，那么目前被广泛使用的高科技方法就没有一个有价值)Such ground selection (指代selecting the ground formations most likely to be mineralized)relies to varying degrees on conceptual models, which take into account theoretical studies of relevant factors.//(第三层：地层选择依赖于概念模型的程度变化，而概念模型要考虑相关因素的理论研究)

These models(指代conceptual models) are constructed primarily from empirical observations of known mineral deposits and from theories of ore-forming processes. The explorer uses the models to identify(概念模型作用之一) those geological features that are critical to the formation of the mineralization being modeled, and then tries to select areas (概念模型作用之二)for exploration that exhibit as many of the critical features as possible.//(第一层：概念模型的建立依据和作用)

逻辑简图：观点对比型

第一段

第一层：介绍最新的关于太古代年龄黄金石英脉系统形成理论。

第二层：介绍与最新理论相悖的被广泛认可的理论。

第二段

第一层：最新理论的重大实践意义：最初发现金矿只需简单地根据砂金痕迹探测，而现在由于大多数金矿埋于地下，不易被发现。

第三段

第一层：金矿勘测的难点以及目前广泛使用的三种探测方法。

第二层：如果勘察的地点从来没有矿化，那么目前被广泛使用的高科技方法就没有一个有价值。

第三层：地层选择依赖于概念模型的程度变化，而概念模型要考虑相关因素的理论研究。

第四段

第一层：概念模型的建立依据和作用。

1.The author is primarily concerned with(主旨题)

A.advocating a return to an older methodology(提倡回归传统方法，不符合原文内容，排除)

B.explaining the importance of a recent theory(解释最近的一种理论的重要性，符合文章内容，正确)

C.enumerating differences between two widely used methods(列举二种被广泛运用的理论的差异，不符合原文内容，排除)

D.describing events leading to a discovery(描述事件导致的发现，不符合原文内容，排除)

E.challenging the assumptions on which a theory is based(质疑建立理论的假设，不符合原文内容，排除)

2.According to the passage, the widely held view of Archean-age gold-quartz vein systems is that such systems(细节题)回文定位至第一段第二层

A.were formed from metamorphic fluids( 正确，对应文中This theory is contrary to the widely held view that the systems were deposited from metamorphic fluids)

B.originated in molten granite-like bodies(层次定位错误， molten granite-like bodies是recent theory中提到的，排除)

C.were formed from alluvial deposits(段落定位错误，alluvial deposits是在最初淘金方法中提到的，排除)

D.generally have surface expression(根据文章，是指 gold deposits exposed at the Earth’s surface，而非gold-quartz vein systems，排除)

E.are not discoverable through chemical tests(根据文章，chemical tests 能够探测出矿化的金矿，所以应是discoverable，排除)

3.The passage implies that which of the following steps would be the first performed by explorers who wish to maximize their chances of discovering gold?(推论题)

A.Surveying several sites known to have been formed more than two billion years ago(文中没有任何信息表明超过20亿年的site更有可能发现金矿，排除)

B.Limiting exploration to sites known to have been formed from metamorphic fluid(文章虽肯定了recent theory的实践意义，但并不意味着要限制探索已知的由metamorphic fluid形成的sites，过分推理，排除)

C.Using an appropriate conceptual model to select a site for further exploration(正确， conceptual models可帮助研究人员找到最有可能矿化的site)

D.Using geophysical methods to analyze rocks over a broad area(根据文章，geophysical methods将没有任何价值如果勘察的地点从来没有矿化，排除)

E.Limiting exploration to sites where alluvial gold has previously been found(根据文章第二段，Although these same methods still lead to an occasional discovery, most deposits not yet discovered have gone undetected because they are buried and have no surface expression，排除)

4.Which of the following statements about discoveries of gold deposits is supported by information in the passage?(细节题)

A.The number of gold discoveries made annually has increased between the time of the original gold rushes and the present.(文章未涉及黄金发现的数量，排除)

B.New discoveries of gold deposits are likely to be the result of exploration techniques designed to locate buried mineralization.(正确，由于大多数金矿埋于地下，探测人员必须找到最有可能含有地下矿石的site)

C.It is unlikely that newly discovered gold deposits will ever yield as much as did those deposits discovered during the original gold rushes.(文章未涉及黄金发现的产量，排除)

D.Modern explorers are divided on the question of the utility of simple prospecting methods as a source of new discoveries of gold deposits.(根据文章，Although these same methods still lead to an occasional discovery, most deposits not yet discovered have gone undetected because they are buried and have no surface expression，现今的探测人员并没有质疑传统方法的效用，排除)

E.Models based on the theory that gold originated from magmatic fluids have already led to new discoveries of gold deposits.(文章并没说在此model指导下找到金矿，排除)

5.It can be inferred from the passage that which of the following is easiest to detect?(推论题)

A.A gold-quartz vein system originating in magmatic fluids(根据文章，这是recent theory的观点，但并没说此gold-quartz vein system 有易于探测的地表显示，排除)

B.A gold-quartz vein system originating in metamorphic fluids(根据文章，这是被广泛认可的观点，但并没说此gold-quartz vein system 有易于探测的地表显示，排除)

C.A gold deposit that is mixed with granite(文章并未涉及gold deposit that is mixed with granite，排除)

D.A gold deposit that has shed alluvial gold(正确，对应文中gold deposits were found because they had shed trails of alluvial gold that were easily easily traced by simple prospecting methods)

E.A gold deposit that exhibits chemical halos(文中第三段第一层提到了关于chemical halos的test，但显然这不是 the easiest means)

6.The theory mentioned in line1-5 relates to the conceptual models discussed in the passage in which of the following ways?(细节题)回文定位至第一段第一层

A.It may furnish a valid account of ore-forming processes, and, hence, can support conceptual models that have great practical significance.(符合原文内容，正确)

B.It suggests that certain geological formations, long believed to be mineralized, are in fact mineralized, thus confirming current conceptual models.(最新理论未确认models，不符合原文内容，排除)

C.It suggests that there may not be enough similarity across Archean-age gold-quartz vein systems to warrant the formulation of conceptual models.(与原文内容相反，根据文章，最近理论有利于 the formulation of conceptual models，排除)

D.It corrects existing theories about the chemical halos of gold deposits, and thus provides a basis for correcting current conceptual models.(不符合原文内容，根据文章，最新理论并未correct existing theories about the chemical halos，相反最新理论还有利于conceptual models的形成和发展，排除)

E.It suggests that simple prospecting methods still have a higher success rate in the discovery of gold deposits than do more modern methods.(最新理论未比较发现金矿的方法，无关方法的比较，排除)

7.According to the passage, methods of exploring for gold that are widely used today are based on which of the following facts?(细节题)

A.Most of the Earth’s remaining gold deposits are still molten.(文章未涉及molten gold，也未涉及探测molten gold的方法，排除)

B.Most of the Earth’s remaining gold deposits are exposed at the surface.(根据文章， most gold deposits are buried，排除)

C.Most of the Earth’s remaining gold deposits are buried and have no surface expression.(符合原文内容，正确)

D.Only one type of gold deposit warrants exploration, since the other types of gold deposits are found in regions difficult to reach.(文章未涉及 types of gold deposits 和 难以探测到的regions，排除)

E.Only one type of gold deposit warrants exploration, since the other types of gold deposits are unlikely to yield concentrated quantities of gold.(文章未涉及types and yields of gold deposits，排除)