请教OG10 272 E

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It is now possible to hear a recording of Caruso’s singing that is far superior to any made during
his lifetime. A decades-old way-cylinder recording of this great operatic tenor has been digitized,
and the digitized signal has been processed by computer to remove the extraneous sound, or
“noise,” introduced by the now “ancient” wax-cylinder recording process.
Although this digital technique needs improvements, it represents a new and superior way of
recording and processing sound which overcomes many of the limitations of analog recording. In
analog recording systems, the original sound is represented as a continuous waveform created by
variations in the sound’s amplitude over time. When analog playback systems reproduce this
waveform, however, they invariably introduce distortions. First, the waveform produced during
playback differs somewhat from the original waveform. Second, the medium that stores the analog
recording creates noise during playback which gets added to the recorded sounds.
Digital recordings, by contrast, reduce the original sound to a series of discrete numbers that
represent the sound’s waveform. Because the digital playback system “reads” only numbers, any
noise and distortion that may accumulate during storage and manipulation of the digitized signal
will have little effect: as long as the numbers remain recognizable, the original waveform will be
reconstructed with little loss in quality. However, because the waveform is continuous, while its
digital representation is composed of discrete numbers, it is impossible for digital systems to avoid
some distortion. One kind of distortion, called “sampling error,” occurs if the sound is sample (i.e.,
its amplitude is measured) too infrequently, so that the amplitude changes more than one quantum
(the smallest change in amplitude measured by the digital system) between samplings. In effect,
the sound is changing too quickly for the system to record it accurately. A second form of
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distortion is “quantizing error,” which arises when the amplitude being measured is not a whole
number of quanta, forcing the digital recorder to round off. Over the long term, these errors are
random, and the noise produced (a background buzzing) is similar to analog noise except that it
only occurs when recorded sounds are being reproduced.
272. Which of the following best describes the relationship of the first paragraph to the passage as
a whole?
(A) The first paragraph introduces a general thesis that is elaborated on in detail elsewhere in
the passage.
(B) The first paragraph presents a concrete instance of a problem that is discussed elsewhere
in the passage.
(C) The first paragraph describes a traditional process that is contrasted unfavorably with a
newer process described elsewhere in the passage.
(D) The first paragraph presents a dramatic example of the potential of a process that is
described elsewhere in the passage.
(E) The first paragraph describes a historic incident that served as the catalyst for
developments described elsewhere in the passage.
请问E选项的“served as the catalyst for developments described elsewhere in the passage”怎么错了啊？我觉得前面的“a historic incident ”错了，而前面的那句应该是对的吧？

lukeleng

(E)第一段描述了一个历史事件,在文章的其它部分对该事件作为促进发展的因素进行了描述,
可是在文章中并没有描述Caruso’s singing 及他的way-cylinder recording 是否促使了或影响其它历史事件的发生.
文章提到Caruso’s singing 及他的way-cylinder recording 只是要举例说明应用Digital recording可以去除analog recording 中的杂音.
文章的结构是总分.第一段提到has been digitized,and the digitized signal has been processed by computer to remove the extraneous ,接下来第二段第一句又说processing,整篇文章都在说这种方法怎样处理声音