步一步教育,详细解析新GRE阅读主旨题(2)

步一步教育,详细解析新GRE阅读主旨题,步一步教育,在GRE阅读中,要想取得高分,对各种题型的分析和总结是至关重要的。如果说,你能够很清楚地掌握出题意图···

The passage focuses primarily on which of the following ……

下面以一篇短阅读为例子来说明：(90年4月阅读真题)

Because of its accuracy in outlining the Earth’s subsurface, the seismic-reflection method remains the most important tool in the search for petroleum reserves. In field practice, a subsurface is mapped by arranging a series of wave-train sources, such as small dynamite explosions, in a grid pattern. As each source is activated, it generates a wave train that moves downward at a speed determined uniquely by the rock’s elastic characteristics. As rock interfaces are crossed, the elastic characteristics encountered generally change abruptly, which causes part of the energy to be reflected back to the surface, where it is recorded by seismic instruments. The seismic records must be processed to correct for positional differences between the source and the receiver, for unrelated wave trains, and for multiple reflections from the rock interfaces. Then the data acquired at each of the specific source locations are combined to generate a physical profile of the subsurface, which can eventually be used to select targets for drilling. The passage is primarily concerned with

(A) Describing an important technique

(B) Discussing a new method

(C) Investigating a controversial procedure

(D) Announcing a significant discovery

(E) Promoting a novel application

分析：

首先，可以确定本文属于结论说明型文章，首句即为这篇文章的topic sentence, “地震波反射仍为探测石油资源的最佳工具”。那么选项A “描述一项重要技术”，与之对应得最好，一

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