“定位”在托福阅读中的应用简单来说一共分为三步：第一步——读题干，找出定位词;第二步——通过题干中的定位词回原文进行定位;第三步——比较定位句与选项的内容，选出语义最接近的选项。朗阁海外考试研究中心的徐老师今日主要为大家分析托福阅读定位法的第三步：

　　一、比较定位句与选项的内容，选出语义最接近的选项

　　注意：

　　1). 考生们所看到的托福阅读定位句可能是一个非常长的句子，而选项相对比较简短，所以考生们一定要学会从长难句中截取你所需要的能回答问题的部分。简单点说就是比如题干中问你why….;那么，此时考生们在分析原文定位句时应该重点看because这种能够解释的部分。

　　2). 考生们在比较定位句与选项时切忌不能随意推理，只需要把握托福阅读文本的字面意思即可。
 

　　例1：

　　Paragraph 3: To what extent competition determines the composition of a community and the density of particular species has been the source of considerable controversy. The problem is that competition ordinarily cannot be observed directly but must be inferred from the spread or increase of one species and the concurrent reduction or disappearance of another species. The Russian biologist G. F. Gause performed numerous two-species experiments in the laboratory, in which one of the species became extinct when only a single kind of resource was available. On the basis of these experiments and of field observations, the so-called law of competitive exclusion was formulated, according to which no two species can occupy the same niche. Numerous seeming exceptions to this law have since been found, but they can usually be explained as cases in which the two species, even though competing for a major joint resource, did not really occupy exactly the same niche. (TPO 29 Competition)

　　Paragraph 3 supports the idea that Gause’s experiments were important because they

　　O provided a situation in which competition could be removed from the interaction between two species

　　O showed that previous ideas about the extent to which competition determines the composition of a community were completely mistaken

　　O helped establish that competition will remove all but one species from any given ecological niche

　　O offered evidence that competition between species is minimal when there is an overabundance of a single food source
 

　　解题步骤：

　　1). 读题干，找出定位词Gause’s experiments, 然后把握托福阅读题目问的内容是有关于G的实验的importance。

　　2). 通过定位词回到托福阅读原文进行定位，位于第三句话。但是第三句只提到了定位词之一，接下来的第四句中提到了由此形成了一个law, 可以对应题干中想问的importance。

　　3). 第3句和第4句两句定位句的大意为“当只有一种食物来源被提供时，两种物种中的一种会消亡。参照这些实验和观察就形成了竞争互斥规律----没有哪两种物种可以占据同样的生态圈”，接下来浏览四个选项，发现C选项大意吻合----确定了竞争将会移除其他所有的物种在任何一个生态圈里面。
 

　　例2：

　　As railroad lines fanned out from Chicago, farmers began to acquire open prairie land in Illinois and then Iowa, putting the fertile, deep black soil into production. Commercial agriculture transformed this remarkable treeless environment. To settlers accustomed to eastern woodlands, the thousands of square miles of tall grass were an awesome sight. Indian grass, Canada wild rye, and native big bluestem all grew higher than a person. Because eastern plows could not penetrate the densely tangled roots of prairie grass, the earliest settlers erected farms along the boundary separating the forest from the prairie. In 1837, however, John Deere patented a sharp-cutting steel plow that sliced through the sod without soil sticking to the blade. Cyrus McCormick refined a mechanical reaper that harvested fourteen times more wheat with the same amount of labor. By the 1850s McCormick was selling 1,000 reapers a year and could not keep up with demand, while Deere turned out 10,000 plows annually. (TPO 33 Railroads and Commercial Agriculture in Nineteenth-Century United States)

　　According to paragraph 5, the first settlers generally did not farm open prairie land because

　　A. they could not plow it effectively with the tools that were available.

　　B. prairie land was usually very expensive to buy.

　　C. the soil along boundaries between the forest and the prairie was more fertile than the soil of the open prairie.

　　D. the railroad lines had not yet reached the open prairie when the first settlers arrived.
 

　　解题步骤：

　　1). 读题干，找出定位词settlers & open prairie land, 并且抓住题干问的重点是because。

　　2). 根据定位词定位到第一句和第三句这样的语义群，这样的语义群可以给我们提供一个大范围定位，然后接下来考生们在第四句里看到了because, 所以第四句就是我们需要的精确定位点。

　　3). 定位句的语义大约为“因为东部的耕种工具无法穿透这里的根部缠结在一起的草，因此，早期的定居者们将农场建立在了远离草原的边界地区。”接下来浏览这篇托福阅读的四个选项，只有A选项提到了因为耕作工具的原因，所以选择A选项。
 

　　二、总结

　　1). 做托福阅读题时必须要先阅读题干，摸清题干所问的具体内容，然后再读文章进行定位。

　　2). 做托福阅读题时既可以只考察某一个特定的定位句理解;同时也可以考察2-3个定位句范围的意群理解。但无论怎样，考生绝对不是漫无目的地搜索，而是根据托福阅读的题干有目的性地寻找答案。

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