Traffic into midtown has decreased by 7 percent, and bus ridership has increased by an
equivalent amount. The mayor's publicity campaign is responsible for this change.
What casts doubt on this conclusion? Another reasonable explanation of what caused
the decrease in automobile traffic and the increase in bus ridership would make this
conclusion suspect. Road construction impeding access to midtown over the same
period of time is a reasonable alternative explanation . The road construction projects
would likely have discouraged people from driving to midtown; many of these people
have probably taken the bus.
A A n increase in fare s might be a reasonable explanation for a decrease in ridership, but not for an
B The mayor's decision to ride the bus sets a good example for citizens, so this would tend to
strengthen rather than weaken support for the conclusion.
C Correct. This statement properly identifies an explanation that weakens support for the
D If more buses were running, then more seats would be available for people traveling into
midtown. Ruling out this scenario help s strengthen, not weaken, support for the conclusion.
E Passengers perceive bus service to be the same, so better service can be eliminated as a possible
cause of the increased ridership .
The correct answer is C .
At the end of the workweek Patrick is paid a certain amount for each hour of child
care he has provided. Patrick usually receives adequate weekly income under this
arrangement, but in the winter Patrick's income fluctuates, because children are
unpredictably absent due to illness.
Which plan would be most likely to meet the two goals of uniform weekly income and adequate
weekly income? Patrick must find a way to ensure that his weekly income is both
adequate- that is, not reduced significantly from current levels-and uniform- that is,
not subject to seasonal or other fluctuations. A successful plan would thus most likely be
one that does not increase Patrick's costs. Further, the plan need not increase Patrick's
weekly income; it must merely ensure that that income is more reliable. It should therefore
also provide some way to mitigate the unexpected loss of income from children's absences.
A This plan might raise Patrick's income slightly, because he and the neighbor might payout less in
costs if they pool their resources. But this plan would have no effect on the problem that
unpredictable absence s pose for Patrick's weekly income.
B Correct. This statement properly identifies a plan that would most likely keep Patrick's income
adequate (he would probably receive approximately the same amount of money per child as he does
now) and uniform (he would receive the money regardless of whether a child was present or absent).
C While this plan might somewhat mitigate the unpredictability in Patrick 's income that results
from sick children's absences- because parents would be less likely to keep sick children at
home-it would increase Patrick 's costs. Paying a helper and investing in different facilities
would reduce Patrick 's income and might thus result in that income being inadequate.
D Under this plan, if we assume that parents did not balk at the increase in Patrick's hourly rate and
find alternative child care, Patrick 's income would most likely be adequate. But this plan would not
help make Patrick's weekly income uniform. H is income would continue to fluctuate when children
are absent. Remember, there are two goals with regard to Patrick's income: adequacy and uniformity.
E This plan might increase Patrick's income, in that he might be paid for more hours of child care
each week. The goals here, however, are to make Patrick 's weekly income both adequate and
uniform, and this plan does not address the issue of uniformity.
The correct answer is B.
Finding that people with low immune-system activity score lower on mental health
tests than people with normal or high levels of immune-system activity, a researcher
concludes that the immune system protects mental as well as physical health.
What assumption does the researcher make? The researcher asserts that immune-system
activity can inhibit mental illness as it does physical illness. While it is possible that
mental illness might itself depress immune-system activity, the researcher assumes
that this is not the case. If mental illness caused a decline in immune-system activity,
then lower levels of immune-system activity would be expected as a result, and the
higher levels would merely indicate the absence of illness rather than any effect on
A The researcher does not distinguish between high and normal levels of immune-system activity,
so this assumption is not needed.
B The researcher's inference is not related to the effects of mental illness.
C Immune-system activity could protect mental health without offering total prevention of mental
illness; this assumption is not needed.
D Correct. This statement properly identifies the researcher's underlying assumption that mental
illness does not decrease immune system activity.
E Since different treatments are not discussed, any assumption about them is unnecessary.
The correct answer is D
The fossil record reveals that species become extinct in a surprisingly definite pattern,
with multiple species vanishing simultaneously.
Which point provides a basis for explaining the pattern ?The passage states that the
process of extinction depends on so many variables-in the ecology and geography
of the environment and in the physiology of the species- that the expected outcome
would be a random pattern of extinctions. Yet a definite pattern is found instead.
What could explain the disappearance of multiple species at the same time? If there
were significant Widespread changes in the environment, multiple species could be
affected simultaneously, causing their extinction.
A Correct. This statement properly identifies a basis for explaining the pattern of many species
becoming extinct simultaneously.
B This explanation of selective extinction does not explain how many species become extinct at the
C This explanation addresses only some species, not many species.
D The passage is based on what the fossil record suggests; more recent times, having no fossil
record, are outside the consideration of the passage.
E Indicating which species are least likely to become extinct does not explain a pattern of
simultaneous extinction of many species.
The correct answer is A.
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发表于 2011-9-27 07:01:39
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