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请教OG12一道题(113)~麻烦帮个忙哈

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发表于 2012-2-3 17:01:01 | 只看该作者 回帖奖励 |倒序浏览 |阅读模式
谁能帮我解释下113题额~是怎么推出来的~又该怎么定位~怎么排除??
原文According to a recent theory,Archean-age
gold-quartz vein systems were formed more than
two billion years ago from magmatic fluids that
originated from molten granite-like bodies deep


(5)   beneath the surface of the Earth. Thistheory is
contrary to the widely held view that the systems
were deposited from metamorphic fluids, that is,
from fluids that formed during the dehydration of
wet sedimentary rocks.

(10)    The recently developed theory hasconsiderable
practical importance. Most of the golddeposits
discovered during the original gold rushes were
exposed at the Earth's surface and were found
because they had shed trails of alluvial gold

(15) that were easily traced bysimple prospecting
methods. Although these same methods still lead
to an occasional discovery, most deposits notyet
discovered have gone undetected because they are
buried and have no surface expression.

(20)    The challenge in exploration is thereforeto
unravel the subsurface geology of an area and
pinpoint the position of buried minerals. Methods
widely used today include analysis of aerial images
that yield a broad geological overview; geophysical

(25) techniques that provide dataon the magnetic,
electrical, and mineralogical properties of the
rocks being investigated; and sensitive chemical
tests that are able to detect the subtle chemical
halos that often envelop mineralization. However,

(30) none of these high-technologymethods are of any
value if the sites to which they are applied have
never mineralized, and to maximize the chances of
discovery the explorer must therefore pay particular
attention to selecting the ground formations most

(35) likely to be mineralized. Suchground selection relies
to varying degrees on conceptual models, which
take into account theoretical studies of relevant
factors.

These models are constructedprimarily from
(40) empirical observations of known mineral deposits
and from theories of ore-forming processes.
The explorer uses the models to identify those
geological features that are critical tothe formation
of the mineralization being modeled, and then tries
(45) to select areas for exploration that exhibit as many
of the critical features as possible.





113.    The theory mentioned in lines 1-5relates to the
conceptual models discussed in the passage in which
of the following ways?


(A)        It may furnish a valid account of ore-forming
processes, and, hence, can support conceptual
models that have great practical significance.


(B)        It suggests that certain geologicalformations,
long believed to be mineralized, are in fact

mineralized, thus confirming current conceptual
models.

(C)   It suggests that there may not be enough
similarity across Archean-age gold-quartz vein
systems to warrant the formulation of
conceptual models.

(D)        It corrects existing theories about the chemical
halos of gold deposits, and thus provides a basis
for correcting current conceptual models.

(E)         It suggests that simple prospecting methods still
have a higher success rate in the discovery of
gold deposits than do more modern methods.



(A)
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