新GRE阅读理解36套每日讨论--51（群178674184）

普渡哥

Geologists have long known that the Earth‘s mantle
is heterogeneous, but its spatial arrangement remains
unresolved—is the mantle essentially layered or irregu-
larly heterogeneous? The best evidence for the layered-
mantle thesis is the well-established fact that volcanic
rocks found on oceanic islands, islands believed to
result from mantle plumes arising from the lower
mantle, are composed of material fundamentally
different from that of the midocean ridge system,
whose source, most geologists contend, is the upper
mantle.
Some geologists, however, on the basis of obser-
vations concerning mantle xenoliths, argue that the
mantle is not layered, but that heterogeneity is created
by fluids rich in “incompatible elements” (elements
tending toward liquid rather than solid state)
percolating upward and transforming portions of the
upper mantle irregularly, according to the vagaries of
the fluids‘ pathways. We believe, perhaps
unimaginatively, that this debate can be resolved
through further study, and that the under explored
midocean ridge system is the key.
(157 words)


10. According to the passage, it is believed that oceanic
islands are formed from
(A) the same material as mantle xenoliths
(B) the same material as the midocean ridge system
(C) volcanic rocks from the upper mantle
(D) incompatible elements percolating up from the
lower mantle
(E) mantle plumes arising from the lower mantle


For the following question, consider each of the choices separately and select all that apply
11. It can be inferred from the passage that the sup-
porters of the ―layered-mantle‖ theory believe which
of the following?
□A The volcanic rocks on oceanic islands are
composed of material derived from the
lower part of the mantle.
□B The materials of which volcanic rocks on
oceanic islands and midocean ridges are
composed are typical of the layers from
which they are thought to originate.
□C The differences in composition between
volcanic rocks on oceanic islands and the
midocean ridges are a result of different
concentrations of incompatible elements.


12. In the context of the passage, “unimaginatively” is
closest in meaning to
(A) pedestrian
(B) controversial
(C) unrealistic
(D) novel
(E) paradoxical

普渡哥

any answers?

sxldos

10. E  11.AB  12.C

普渡哥

正确答案：
10. E 11. AB 12. A

大家周末继续加油啊!