GWD32—32-34
The dry mountain ranges of the
western United
States contain rocks
dating back
440 to 510 million years,
Line to the Ordovician period, and teeming
1)
with evidence of tropical marine life.
This rock
record provides clues about
one of
the most significant radiations
(periods when
existing life-forms gave
rise to variations
that would eventually
10) evolve into entirely new species) in the
history of marine
invertebrates. During
this radiation the
number of marine
biological
families increased greatly,
and these families
included species
15) that would dominate the marine ecosys-
tems of the area
for the next 215 million
years. Although
the radiation span-
ned tens of
millions of years, major
changes in many
species occurred
20) during a geologically short time span
within the
radiation and, furthermore,
appear to have
occurred worldwide,
suggesting that
external events were
major factors in
the radiation. And , in
25) fact, there is evidence of major eco-
logical and
geological changes during
this period: the
sea level dropped
drastically and
mountain ranges were
formed, in this
instance, rather than
30) leading to large-scale extinctions,
these kinds of
environmental changes
may have resulted
in an enriched pat-
tem of habitats
and nutrients, which in
turn gave rise to
the Ordovician radi-
35) ation. However, the actual relationship
between these
environmental factors
and the
diversification of life forms is
not yet fully
understood
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Q4
The passage is primarily
concerned with
A. evaluating
the evidence of a major geologic period and determining its duration
B. describing
an evolutionary phenomenon and speculating about its cause
C. explaining
the mechanisms through which marine life-forms evolved during a particular
period
D. analyzing
the impact on later life-forms of an important evolutionary development
E. contrasting
a period of evolutionary change with other such periods 这题给的答案是C, 我选了B. 不知大家意见如何？
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Q5
Which of the following can
be inferred from the passage regarding the geologic changes
that occurred during
Ordovician period?
A. They
were more drastic than those associated with other radiations
B. They
may have created conditions favorable to the evolution of many new life-forms
C. They
may have caused the extinction of many of the marine species living in shallow
waters
D. They
may have been a factor in the development of new species adapted to living both
on land and in water
E. They
hastened the formation of the extensive dry regions found in the western united
states 这题给的答案是E, 我选了B.
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Q6
Which of the following best
describes the function of last sentence of the passage ?
A. it
points out that the events described in the passage may be atypical
B. it
alludes to the fact that there is disagreement in the scientific community over
the importance of the Ordovician radiation
C. it
concludes that the evidence presented in the passage is insufficient to support
the proposed hypothesis because it comes from a limited geographic area
D. it
warns the reader against seeing a connection between the biological and geolgic
changes described in the passage
E. it
alerts the reader that current knowledge cannot completely explain the
relationship suggested by the evidence presented in the passage 这题给的答案是E, 我没有异议。
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发表于 2007-10-28 12:17:00
