做雅思阅读 记雅思单词：Multiple Choice Question

　　做MATCHING 题目时，最重要的一点就是找到关键词。拿到一篇文章后，首先浏览文章标题，然后把题目中列出的关键词逐个找到，并将该词所在的句子用线划出。然后，我们就可以根据划线句子的意思与问题给出的备选项进行对照，意思相近或相符的那一句就应该是正确答案。发现两个句子意思相近或相符的关键是找原句中的同义词或近义词，这样就可大大减少阅读量，从而能在较短的时间内找到答案。如果答案不能在出现关键词的句子中找到，就应从该句的上下文中去寻找答案。还有些时候，你会发现关键词在好几个句子中都出现了。这时，你可以将这几个句子都划出来，与备选项中的句子逐个对照，意思相近的就是正确选项。

　　还有一个需要注意的问题是，每选定一个答案后，应把已选好的选项用线划掉，以免影响后面的判断。

　　下面，我们就以下文为例具体进行分析。

　　Geophysics For Utility Location:

　　When It Works - When It Wont

　　Utility companies, construction projects, and highway contractors are often faced with the need to excavate or pipe-jack in the vicinity of known or suspected buried utility lines, drains, or other subsurface structures. In many cases, particularly where they are adjacent to highways, the lateral position of the lines may be documented with reasonable accuracy, but the vertical position, or burial depth, may be uncertain due to changes in grade caused by construction or maintenance performed after the pipes were buried.

　　One way to verify the location of such buried objects is to cautiously dig a trial pit to expose the object in question. However, digging such a pit in or close to a highway is costly because of the need for traffic control, and subsequent reinstatement of the surface to meet the original specification. There is also a substantial risk of accident and personal injury, partly due to the disruption caused to the highway traffic, and partly due to the nature of the work. Where mechanical digging equipment is used, an undocumented or misaligned utility line can easily be damaged if the excavation workers do not observe it. Gas and electricity lines present very obvious safety threats in this situation.

　　These factors have caused utility engineers and contractors to search for alternative methods to locate subsurface structures, often with mixed success. There are several geophysical techniques with proven capabilities in non-intrusive subsurface investigation, but there are less publicized limitations to these methods that potential specifies and users should be aware of if they are to avoid inconclusive or misleading survey reports.

　　Practical Near-Surface Techniques

　　The real driving force behind the development of geophysical survey methods was the search for oil and other valuable mineral deposits. The earlier methods were therefore primarily focused on the detection and identification of relatively large geological formations at depths that were typically measured in several hundreds of feet. Such methods do not have the resolution to detect small objects, such as pipelines and cables, buried only a few feet deep.