油酸那道题的分析，向N们求证！

便于回帖，重发新贴

The quality of unrefined olive oil is not actually defined in terms of acidity, yet extensive tests have shown that the less free oleic acid an unrefined olive oil contains per liter, the higher its quality.  The proportion of free oleic acid that an olive oil contains is an accurate measure of the oil’s acidity.

If the statements above are all true, which of the following conclusions is best supported by them?

1. When an olive oil is refined, the concentration of oleic acid in the oil is reduced.
   
2. The quality of an unrefined olive oil can be determined only by accurately measuring its acidity.
   
3. If an unrefined olive oil is intermediate in acidity between two other unrefined olive oils, it will also be intermediate between them in quality.
   
4. Free oleic acid is the only acid that unrefined olive oil contains.
   
5. People who judge the quality of unrefined olive oils actually judge those oils by their acidity, which the judges can taste.

看了大家的讨论我却觉着应该选b，呵呵，不要砸我

明确：此题要求承认 the statements above are all true, which of the following conclusions is best supported by them? 请注意是“by them”,要由论述内容间的联系和逻辑推理得出，而不是仅针对某一点得出结论，或者借助背景知识得出。

那题目中说了什么呢？

首先，提出The quality of unrefined olive oil is not actually defined in terms of acidity，

接着，用“yet”提出了（就像阅读中，提出不同观点的标志词）：extensive tests have shown that the less free oleic acid an unrefined olive oil contains per liter, the higher its quality  （我们可与看到这里主要是阐述“free oleic acid”和“its quality”的关系，那我们就会想了，这个“free oleic acid ”和开头提出的“acidity”有没有关系呢？又是怎样的关系呢，明确了它们的关系，才知道作者的不同观点是什么）

于是，我们就看到了“The proportion of free oleic acid that an olive oil contains is an accurate measure of the oil's acidity.”（这里说明油中proportion of free oleic acid 是油的“acidity”的“an accurate measure”，明确了不同观点中提出的“ free oleic acid ”和开头观点中的对象“acidity”的关系）

按照这个逻辑，我们可以看出题目中三个对象关系即： “free oleic acid ”充当了桥梁的作用，把题目中的另外两个对象“quality of an unrefined olive oil”和“ its acidity”联系起来了。

则我们可得出这个不同观点（确切的说应该是更精确的观点）的结论，即：

The quality of an unrefined olive oil can be determined only by accurately measuring its acidity

黑体部分可以看出，以上推理得出的结论是比文章开头提出观点的更严密的观点。

看看其他选项：

A.When an olive oil is refined, the concentration of oleic acid in the oil is reduced.   

无法单纯由题目中陈述的内容推出来的，而且“refined”题目中也未涉及，另外，该选项也未涉及有关酸和质量的推论，所以排除；

C. If an unrefined olive oil is intermediate in acidity between two other unrefined olive oils, it will also be intermediate between them in quality.

只是针对不同观点的内容进行了举例，没有利用 The proportion of free oleic acid that an olive oil contains is an accurate measure of the oil's acidity.这点信息，所以非全面结论。

D.Free oleic acid is the only acid that unrefined olive oil contains.

只是针对 The proportion of free oleic acid that an olive oil contains is an accurate measure of the oil's acidity.这点信息得出的推论，非全面结论。

E. People who judge the quality of unrefined olive oils actually judge those oils  by their acidity, which the judges can taste.

该选项增加了跟题目推论无关的对象“people...acidity, which the judges can taste”所以最容易排除。

the answer is C, first as what you mention, A, D, and E are easy to eliminate. but B is also problematic because of the word "only", the passage provide evidence that that it is more reliable criteria, but did not say it is the only and exclusive measurement.

C, the best choice, gives example indicating what is mentioned in passage, "less free oleic acid an unrefined olive oil contains per liter, the higher its quality". There are three unrefined olive oil, X,Y, Z, with respective acidity, x, y, z, x<y<z. then the quality of these olive oils are ordered as X>Y>Z.  

你论证中的一个错误是“conclusion"需要用到题目中的所有条件。这是不一定的。所谓逻辑，是一种推理“线性”关系，也就是关于逻辑中各个元素之间的关系。在GMAT逻辑中，从来没有要求结论要基於问题所有条件。某条件A能等到B，B就是结论。我印象中很多结论题目的答案都不是和所有条件有关。做结论题要对原文理解透彻，验证结论的方法如“假设”题，如果此结论不正确，那么原文所给的某个条件必为非。但是我并不建议用这种方法来找答案，如果理解透彻，答案会更直接。

大家热心回复，感动！

To Maggieyin:

1. 看来这里的“only”我们理解不同，在我看来"only"强调了“accurately measuing”,而不是强调" by measuring its acidity ”为唯一方式, 我不知道是否说明白了我的意思，但看其他选项出了这一点有歧义外，应该是最优的吧？！

2。如果选c，那最后一句话The proportion of free oleic acid that an olive oil contains is an accurate measure of the oil's acidity.在题目中起什么作用呢？

To mindfree:

1、我并没有强调要求要用到所有条件，我赞同你所说的“所谓逻辑，是一种推理“线性”关系，也就是关于逻辑中各个元素之间的关系。”的观点，所以我的推论是基于对题目中涉及的对象（你指的元素），以及它们之间的关系进行的，但这道题根据这个原则的确是要用到所有给出的条件，否则，按提供的选项，答案就不只一个了，如d。

2、按照你给出的方法，答案应该是哪个呢？呵呵，就像 lawyer_1 所说的 “前提条件是你知道该选项从原文的那句话或那个结果推出，问题是这个条件很难做到”，对这道题来说尤其如此。

hi, cindy, mindfree ana lawyer have pointed the fundamentals dealing with this type of question.

if I am right, I understand you are talking about accurate measuring results and a measuring standard. for both case, the word of "only" gives abolute limitation. Perhaps both will be true in the future after taking further scientific experiments, but there is no content showing it uniqueness in the passage now.  if the "only" is omitted, B will be a good choice.

it is a new conclusion "The proportion of free oleic acid that an olive oil contains is an accurate measure of the oil's acidity " . I agree with you.

这道题昨天做题时选的C, 可今天分析的时候, 我又倾向于A, 到底应是哪个?

我觉着根据原文, 对unrefined oil来说, oleic acid是它quality的一个参数, 但acidity却不是, 说明oleic acid和acidity没有直接的联系, 那么C的断桥就接不起来,C不成立.

对olive oil来说, oleic acid和acidity却有直接的对应关系, 说明在提炼的过程中其他杂质酸的concentration降低了, 但olive oil是否降低, 我就弄不清了, 但也有可能降低,所以我倾向A.

大家看我是否错了, 到底是哪个正确?