The primary purpose of the passage is to… (目的性主旨题)
The author is primarily concerned with… (目的性主旨题)
Which of the following best states the central idea of the passage? (目的性主旨题)
… best describes the organization of… (写法性主旨题)
Which of the following is the most accurate description of the organization of…? (写法性主旨题)
In developing the main idea of the passage, the author dose which of the following? (写法性主旨题)
Which of the following is the most appropriate title for the passage? (标题题)
The passage would be most likely to appear as a part of… (变相主题题)
a) 从文章入手指的是着重分析文章段落的首句(Topic Sentence)，因为往往正确选项都是TS的改写。分析的时候有一点要注意的，那就是TS并不绝对是每段的最后一句话，而有可能是文章的第二句甚至是第三句话。
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.
Which of the following best describes the organization of the passage?
(A)A method is criticized, and an alternative is suggested.
(B)An illustration is examined, and some errors are exposed.
(C)An assertion is made, and a procedure is outlined.
(D)A series of examples is presented, and a conclusion is drawn.
(E)A hypothesis is advanced, and supporting evidence is supplied.
分析：作者在文章的第一句话(TS)中就提出了自己的观点：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.在理解了这句话后，我们排查五个选项，发现C选项是唯一对TS的解释，所以是正确选项。