|
觉得这篇是OG RC中逻辑关系最复杂的一篇了，然后今天我仔细的总结了一下，原文中的关键词句加了高亮，把每道题能够回归原文找到答案的都用颜色画出来了，文章后面还有我总结的逻辑推理步骤。呵呵，希望大家一起来讨论一下这篇啊~~~
According to a recent theory, 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 (5) beneath the surface of the Earth. This theory is contrary to the widely held view that the systems were deposited from metamorphic fluids, that is, from fluids that formed during the dehydration of wet sedimentary rocks.
(10) The recently developed theory has considerable practical importance. 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 (15) that were easily traced by simple prospecting methods. 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. (20) The challenge in exploration is therefore to unravel the subsurface geology of an area and pinpoint the position of buried minerals. Methods widely used today include analysis of aerial images that yield a broad geological overview; geophysical (25) techniques that provide data on the magnetic, electrical, and mineralogical properties of the rocks being investigated; and sensitive chemical tests that are able to detect the subtle chemical halos that often envelop mineralization. However,(30) none of these high-technology methods are of any value if the sites to which they are applied have never mineralized, and to maximize the chances of discovery the explorer must therefore pay particular attention to selecting the ground formations most (35) likely to be mineralized. Such ground selection relies to varying degrees on conceptual models, which take into account theoretical studies of relevant factors. These models are constructed primarily from (40) empirical observations of known mineral deposits and from theories of ore-forming processes. The explorer uses the models to identify those geological features that are critical to the formation of the mineralization being modeled, and then tries (45) to select areas for exploration that exhibit as many of the critical features as possible. 每段大意： 1. a recent theory, contrary to widely held view 2. practical importance, most deposits have no surface expression 3. ( because of no surface expression), methods today, high-tech, however, high-tech useless if no mineralized, so detect whether mineralized is important. Detect mineralized take conceptual models from observations and the theory 4. So, what explorers should do 二、三段逻辑关系：How the author proves the theory is practically important? Gold that have surface expression has been discovered in gold-rush à no surface expression àhave to use high-tech today However, high-tech useless, if not mineralized à important to detect whether mineralized And, the method used to detect mineralized is from both observation and the theory à the theory is important Questions 103-110 refer to the passage on page 382. 103.
The author is primarily concerned with (A) advocating a return to an older methodology (B) explaining the importance of a recent theory (C) enumerating differences between two widely used methods (D) describing events leading to a discovery (E) challenging the assumptions on which a theory is based Main idea Examine the entire passage to find the author’s primary concern. An analysis of this passage shows that the author introduces a recent theory in the first paragraph, explains the practical importance of the theory in the second, and discusses the methods of exploration the theory makes possible in the third and fourth paragraphs. The author is primarily concerned with presenting a new theory and showing why it is important. A The only older methodology cited in the passage, simple prospecting methods, leads to only an occasional discovery (lines 15-17). B Correct. The author describes a recent theory of ore formation and discusses its importance. C Three methods of exploration are described in the third paragraph, but differences among them are not discussed. D The passage describes a theory and the practice derived from it; it does not describe a series of events leading to a discovery. E The author describes two theories of ore formation in the first paragraph but does not challenge the assumptions on which either one is based. The correct answer is B. 104.
According to the passage,
the widely held view of Archean-age gold-quartz vein systems is that such systems (A) were formed from metamorphic fluids 原文 (B) originated in molten granite-like bodies 新观点 (C) were formed from alluvial deposits (D) generally have surface expression （most deposits…. have no surface expression） (E) are not discoverable through chemical tests Supporting ideas This question asks for information explicitly stated in the first paragraph where Archean-age gold‑ quartz vein systems are discussed. The recent theory is contrary to the widely held theory that Archean-age gold quartz vein systems were deposited from metamorphic fluids (lines 6-7). A Correct. The widely held theory explains that the systems were formed from metamorphic fluids. B It is the recent theory that holds that the systems were formed from magmatic fluids that originated from molten granite-like bodies (lines 3-4); the recent theory is not the widely held view. C Alluvial deposits are mentioned only in the context of simple prospecting methods (lines 15‑ 16). D Lines 18-19 explain that most deposits have no surface expression. E Sensitive chemical tests are able to detect deposits where mineralization has occurred (lines 27‑ 28). The correct answer is A. 105.
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? (A) Surveying several sites known to have been formed more than two billion years ago (B) Limiting exploration to sites known to have been formed from metamorphic fluid (C) Using an appropriate conceptual model to select a site for further exploration (D) Using geophysical methods to analyze rocks over a broad area (E) Limiting exploration to sites where alluvial gold has previously been found Inference Since the question uses the word implies, the answer will be an inference based on what the passage says about exploration. The third and fourth paragraphs describe the process of exploration. The high-technology methods are of no use to the explorer if the sites have not mineralized, and to maximize the chances of discovery the explorer must therefore pay particular attention to selecting the ground formations most likely to be mineralized (lines 32-35). Conceptual models based on observation and ore-formation theories allow the explorer to identify the areas most likely to be mineralized (lines 34-35). A The passage does indicate that age is a factor in selecting a site. B The earlier theory, rather than the recent theory that is the focus of the passage, argued that gold vein systems were formed from metamorphic fluids. The passage says the recent theory has considerable practical importance, suggesting the benefits of applying the newer theory rather than this earlier theory. C Correct. Conceptual models lead the explorer to the sites most likely to have mineralized. D Geophysical techniques are of no use unless an area has been mineralized (lines 30-33). E The simple prospecting methods that find alluvial gold lead to only an occasional discovery, most deposits are buried (lines 15-17). The correct answer is C. 106.
Which of the following statements about discoveries of gold deposits is supported by information in the passage? (A) The number of gold discoveries made annually has increased between the time of the original gold rushes and the present. 没说 (B) New discoveries of gold deposits are likely to be the result of exploration techniques designed to locate buried mineralization. (C) It is unlikely that newly discovered gold deposits will ever yield as much as did those deposits discovered during the original gold rushes. 没说 (D) Modern explorers are divided on the question of the utility of simple prospecting methods as a source of new discoveries of gold deposits. (E) Models based on the theory that gold originated from magmatic fluids have already led to new discoveries of gold deposits. 没说 Supporting ideas This question requires consideration of explicit information throughout the passage. The second paragraph explains that most deposits are buried (lines 17-19), so the explorer’s best means of discovering them is the use of conceptual models to identify the sites most likely to have buried mineralization (lines 35-38). At that point, the explorer may use the high-technology methods possible when buried mineralization is present (lines 22-29). A The passage does not discuss the number of gold discoveries. B Correct. Since most gold deposits are buried, explorers must find the sites most likely to contain buried mineralization. C The passage does not discuss the yield of gold discoveries. D While simple prospecting methods lead only to an occasional discovery, modem explorers are not said to dispute their utility. E The passage does not say that gold deposits have already been found by using the models based on this recent theory. The correct answer is B. 107.
It can be inferred from the passage that which of the following is easiest to detect? (A) A gold-quartz vein system originating in magmatic fluids (B) A gold-quartz vein system originating in metamorphic fluids (C) A gold deposit that is mixed with granite (D) A gold deposit that has shed alluvial gold （were found because they had shed trails of alluvial gold (15) that were easily traced by simple prospecting methods.） (E) A gold deposit that exhibits chemical halos Application To answer this question, apply what the passage says about gold deposits to the examples in the answer choices. The second paragraph states that the gold deposits discovered during the gold rushes were exposed at the Earth’s surface, they were found because they had shed trails of alluvial gold that were easily traced by simple prospecting methods (lines 12-16). Most deposits have not been detected because they are buried and have no surface expression. Thus the simplest gold o find would he that in a deposit that had shed alluvial gold. A The recent theory holds that gold-quartz vein systems are formed from magmatic fluids, but does not say that these systems have easily detectable surface expressions. B The widely held theory contends that gold-quartz vein systems are formed from metamorphic fluids, but does not say whether these have easily detectable surface expressions. C The passage does not comment on gold deposits mixed with granite, although the recent theory does mention molten granite‑
like bodies deep beneath the surface of the Earth (lines 4-5). D Correct. Finding gold deposits that have shed alluvial gold at the Earth’s surface is far easier than finding buried gold deposits. E One complex, difficult subsurface exploration method involves chemical tests detecting the subtle chemical halos that surround mineralized areas; clearly this is not the easiest means of detecting gold deposits. The correct answer is D. 108.
The theory mentioned in line 1 relates to the conceptual models discussed in the passage in which of the following ways? (A) It may furnish a valid account of ore-forming processes, and, hence, can support conceptual models that have great practical significance. (B) It suggests that certain geological formations, long believed to be mineralized, are in fact mineralized, thus confirming current conceptual models. (C) It suggests that there may not be enough similarity across Archean-age gold-quartz vein systems to warrant the formulation of conceptual models. (D) It corrects existing theories about the chemical halos of gold deposits, and thus provides a basis for correcting current conceptual models. (E) It suggests that simple prospecting methods still have a higher success rate in the discovery of gold deposits than do more modern methods. Logical Structure This question requires considering the conceptual models described in lines 35-38 in light of the recent theory (lines 1-4), which the author assures the reader has considerable practical importance (lines 10-11). The conceptual models are derived from observation and from theories of ore forming processes. Therefore, the recent theory may explain ore formation in a way that leads to the development of an updated model, and that model may then aid in the discovery of gold deposits. A Correct. The theory provides an explanation of ore formation, which aids in creating a conceptual model that may help explorers find gold deposits. B The theory does not confirm models, but contributes o forming them. C The practical value of the theory is that it can help to formulate models. D The theory does not challenge theories about chemical halos but rather contributes to the development of conceptual models that might allow for their broader application. E The theory does not compare methods of discovering gold deposits. The correct answer is A. 109.
According to the passage, methods of exploring for gold that are widely used today are based on which of the following facts? (A) Most of the Earth’s remaining gold deposits are still molten. (B) Most of the Earth’s remaining gold deposits are exposed at the surface. (C) Most of the Earth’s remaining gold deposits are buried and have no surface expression. Nowadays用高科技手段也可以证明，如果表面就有，用简单的判断方法就行了，不用高科技 (D) Only one type of gold deposit warrants exploration, since the other types of gold deposits are found in regions difficult to reach. (E) Only one type of gold deposit warrants exploration, since the other types of gold deposits are unlikely to yield concentrated quantities of gold. Supporting ideas As indicated by the phrase according to the passage, this question concerns factual information stated in the passage. In contrast to the gold deposits discovered at the Earth’s surface, most deposits not yet discovered have gone undetected because they arc buried and have no surface expression (lines 17-19). The methods used widely today must search for buried minerals rather than minerals on the surface (lines 22-29). A The passage mentions neither molten gold nor the method o detect it. B The passage explicitly says that most deposits are buried. C Correct. The passage explicitly states that most gold deposits are buried, leaving no traces at the Earth’s surface. D The passage neither distinguishes between types of gold nor describes inaccessible regions. E The passage does not describe types or yields of gold deposits. The correct answer is C. 110.
It can be inferred from the passage that the efficiency of model-based gold exploration depends on which of the following? I. The closeness of the match between the geological features identified by the model as critical and the actual geological features of a given area 原文：then tries (45) to select areas for exploration that exhibit as many of the critical features as possible. II. The degree to which the model chosen relies on empirical observation of known mineral deposits rather than on theories of ore‑ forming processes 原文：These models are constructed primarily from (40) empirical observations of known mineral deposits and from theories of ore-forming processes. Model constructed from both observations and processes, 没说哪个更重要 III. The degree to which the model chosen is based on an accurate description of the events leading to mineralization 原文：none of these high-technology methods are of any value if the sites to which they are applied have never mineralized, and to maximize the chances of discovery the explorer must therefore pay particular attention to selecting the ground formations most (35) likely to be mineralized. Mineralized 的重要性，所以准确判断是否mineralized很关键 (A) I only (B) II only (C) I and II only (D) I and III only (E) II, and III Inference The question requires a close reading of the final paragraph to find information that is suggested but not directly stated. The first sentence says that the models are derived from both observation and theories, but observation is not weighed more heavily than the theories, so statement H can be eliminated. The next sentence says that models help explorers identify, those geological features that are critical to the formation of the mineralization being modeled, and then tries to select areas for exploration that exhibit as many of the critical features as possible. The efficiency of the exploration is affected by the match between the critical features the model identifies and the critical features of the actual site: the closer the match, the greater the efficiency. Thus statement I is true. The more accurate the model is in describing mineralization, the greater the likelihood of selecting an appropriate site, which increases the efficiency of exploration. Statement HI must be true as well. Therefore, the correct answer includes statements I and III, while excluding statement II. A I must be included, but so must III. B II misstates the information in lines 33-35. C I is necessary, but II must be excluded. D Correct. Both I and III give reasons for the greater efficiency of exploration. E I and III are necessary, but H must be excluded. The correct answer is D.
[此贴子已经被作者于2008-5-5 22:44:43编辑过] | 
京公网安备11010202008513号 京ICP证101109号 京ICP备12012021号
发表于 2008-5-5 22:41:00
楼主
