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1答疑

[Reading Comprehension]

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文章：

Line         After evidence was obtained in the 1920s that
  the universe is expanding, it became reasonable to
  ask: Will the universe continue to expand
  indefinitely, or is there enough mass in it for the
(5) mutual attraction of its constituents to bring this
  expansion to a halt? It can be calculated that the
  critical density of matter needed to brake the
  expansion and “close” the universe is equivalent
  to three hydrogen atoms per cubic meter. But the
(10) density of the observable universe—luminous
  matter in the form of galaxies—comes to only a
  fraction of this. If the expansion of the universe is
  to stop, there must be enough invisible matter in
  the universe to exceed the luminous matter in
(15) density by a factor of roughly 70.
       Our contribution to the search for this “missing
  matter” has been to study the rotational velocity of
  galaxies at various distances from their center of
  rotation. It has been known for some time that
(20) outside the bright nucleus of a typical spiral galaxy
  luminosity falls off rapidly with distance from the
  center. If luminosity were a true indicator of mass,
  most of the mass would be concentrated toward
  the center. Outside the nucleus the rotational
(25) velocity would decrease geometrically with
  distance from the center, in conformity with
  Kepler’s law. Instead we have found that the
  rotational velocity in spiral galaxies either remains
  constant with increasing distance from the center
(30) or increases slightly. This unexpected result
  indicates that the falloff in luminous mass with
#160; distance from the center is balanced by an
  increase in nonluminous mass.
       Our findings suggest that as much as 90 percent
(35) of the mass of the universe is not radiating at any
  wavelength with enough intensity to be detected
  on the Earth. Such dark matter could be in the
  form of extremely dim stars of low mass, of large
  planets like Jupiter, or of black holes, either small
(40) or massive. While it has not yet been determined
  whether this mass is sufficient to close the universe,
  some physicists consider it significant that estimates
  are converging on the critical value.


题目：

The authors’ study indicates that, in comparison with the outermost regions of a typical spiral galaxy, the region just outside the nucleus can be characterized as having

选项:

A、higher rotational velocity and higher luminosity
B、lower rotational velocity and higher luminosity
C、lower rotational velocity and lower luminosity
D、similar rotational velocity and higher luminosity
E、similar rotational velocity and similar luminosity

答案:

D
1答疑

[Reading Comprehension]

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文章：

Line         In Winters v. United States (1908), the Supreme
  Court held that the right to use waters flowing through
  or adjacent to the Fort Belknap Indian Reservation
  was reserved to American Indians by the treaty
(5) establishing the reservation. Although this treaty did
  not mention water rights, the Court ruled that the
  federal government, when it created the reservation,
  intended to deal fairly with American Indians by
  reserving for them the waters without which their
(10) lands would have been useless. Later decisions, citing
  Winters, established that courts can find federal rights
  to reserve water for particular purposes if (1) the
  land in question lies within an enclave under exclusive
  federal jurisdiction, (2) the land has been formally
(15) withdrawn from federal public lands—i.e., withdrawn
  from the stock of federal lands available for private
  use under federal land use laws—and set aside
  or reserved, and (3) the circumstances reveal the
  government intended to reserve water as well as land
(20) when establishing the reservation.
       Some American Indian tribes have also established
  water rights through the courts based on their
  traditional diversion and use of certain waters prior
  to the United States’ acquisition of sovereignty. For
(25) example, the Rio Grande pueblos already existed
  when the United States acquired sovereignty over
  New Mexico in 1848. Although they at that time
  became part of the United States, the pueblo lands
  never formally constituted a part of federal public
(30) lands; in any event, no treaty, statute, or executive
  order has ever designated or withdrawn the pueblos
  from public lands as American Indian reservations.
  This fact, however, has not barred application of the
  Winters doctrine. What constitutes an American Indian
(35) reservation is a question of practice, not of legal
  definition, and the pueblos have always been treated
  as reservations by the United States. This pragmatic
  approach is buttressed by Arizona v. California (1963),
  wherein the Supreme Court indicated that the manner
(40) in which any type of federal reservation is created
  does not affect the application to it of the Winters
  doctrine. Therefore, the reserved water rights of
  Pueblo Indians have priority over other citizens’ water
  rights as of 1848, the year in which pueblos must be
(45) considered to have become reservations.


题目：

The “pragmatic approach” mentioned in lines 37–38 of the passage is best defined as one that

选项:

A、grants recognition to reservations that were never formally established but that have traditionally been treated as such
B、determines the water rights of all citizens in a particular region by examining the actual history of water usage in that region
C、gives federal courts the right to reserve water along with land even when it is clear that the government originally intended to reserve only the land
D、bases the decision to recognize the legal rights of a group on the practical effect such a recognition is likely to have on other citizens
E、dictates that courts ignore precedents set by such cases as Winters v. United States in deciding what water rights belong to reserved land

答案:

A
1答疑

[Critical Reasoning]

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题目：

The senator has long held to the general principle that no true work of art is obscene, and thus that there is no conflict between the need to encourage free artistic expression and the need to protect the sensibilities of the public from obscenity. When well-known works generally viewed as obscene are cited as possible counterexamples, the senator justifies accepting the principle by saying that if these works really are obscene then they cannot be works of art.
The senator’s reasoning contains which one of the following errors?

选项:

A、A. It seeks to persuade by emotional rather than intellectual means.
B、B. It contains an implicit contradiction.
C、C. It relies on an assertion of the senator's authority.
D、D. It assumes what it seeks to establish.
E、E. It attempts to justify a position by appeal to an irrelevant consideration.

答案:

D
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[Critical Reasoning]

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题目：

Parland’s alligator population has been declining in recent years, primarily because of hunting. Alligators prey heavily on a species of freshwater fish that is highly valued as food by Parlanders, who had hoped that the decline in the alligator population would lead to an increase in the numbers of these fish available for human consumption. Yet the population of this fish species has also declined, even though the annual number caught for human consumption has not increased.

Which of the following, if true, most helps to explain the decline in the population of the fish species?

选项:

A、The decline in the alligator population has meant that fishers can work in some parts of lakes and rivers that were formerly too dangerous.
B、Over the last few years, Parland’s commercial fishing enterprises have increased the number of fishing boats they use.
C、The main predator of these fish is another species of fish on which alligators also prey.
D、Many Parlanders who hunt alligators do so because of the high market price of alligator skins, not because of the threat alligators pose to the fish population.
E、In several neighboring countries through which Parland’s rivers also flow, alligators are at risk of extinction as a result of extensive hunting.

答案:

C
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[Critical Reasoning]

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题目：

Archaeologist: Researchers excavating a burial site in Cyprus found a feline skeleton lying near a human skeleton. Both skeletons were in the same sediment at the same depth and equally well-preserved, suggesting that the feline and human were buried together about 9,500 years ago. This shows that felines were domesticated around the time farming began, when they would have been useful in protecting stores of grain from mice.

Which of the following, if true, would most seriously weaken the archaeologist’s argument?

选项:

A、Archaeologists have not found any remains of stores of grain in the immediate vicinity of the burial site.
B、The burial site in Cyprus is substantially older than any other known burial site in which a feline skeleton and a human skeleton appear to have been buried together.
C、Paintings found near the burial site seem to show people keeping felines as domestic companions, but do not show felines hunting mice.
D、In Cyprus, there are many burial sites dating from around 9,500 years ago in which the remains of wild animals appear to have been buried alongside human remains.
E、Before felines were domesticated, early farmers had no effective way to protect stores of grain from mice.

答案:

D
1答疑

[Reading Comprehension]

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文章：

In terrestrial environments, gravity places special demands on the cardiovascular systems of animals. Gravitational pressure can cause blood to pool in the lower regions of the body, making it difficult to circulate blood to critical organs such as the brain. Terrestrial snakes, in particular, exhibit adaptations that aid in circulating blood against the force of gravity.

The problem confronting terrestrial snakes is best illustrated by what happens to sea snakes when removed from their supportive medium. Because the vertical pressure gradients within the blood vessels are counteracted by similar pressure gradients in the surrounding water, the distribution of blood throughout the body of sea snakes remains about the same regardless of their orientation in space, provided they remain in the ocean. When removed from the water and tilted at various angles with the head up, however, blood pressure at their midpoint drops significantly, and at brain level falls to zero. That many terrestrial snakes in similar spatial orientations do not experience this kind of circulatory failure suggests that certain adaptations enable them to regulate blood pressure more effectively in those orientations.

One such adaptation is the closer proximity of the terrestrial snake’s heart to its head, which helps to ensure circulation to the brain, regardless of the snake’s orientation in space. The heart of sea snakes can be located near the middle of the body, a position that minimizes the work entailed in circulating blood to both extremities. In arboreal snakes, however, which dwell in trees and often assume a vertical posture, the average distance from the heart to the head can be as little as 15 percent of overall body length. Such a location requires that blood circulated to the tail of the snake travel a greater distance back to the heart, a problem solved by another adaptation. When climbing, arboreal snakes often pause momentarily to wiggle their bodies, causing waves of muscle contraction that advance from the lower torso to the head. By compressing the veins and forcing blood forward, these contractions apparently improve the flow of venous blood returning to the heart.

题目：

It can be inferred from the passage that which of the following is true of species of terrestrial snakes that often need to assume a vertical posture?

选项:

A、They are more likely to be susceptible to circulatory failure in vertical postures than are sea snakes.Their hearts are less likely to be located at the midpoint of their bodies than is the case with sea snakes.
B、They cannot counteract the pooling of blood in lower regions of their bodies as effectively as sea snakes can.
C、The blood pressure at their midpoint decreases significantly when they are tilted with their heads up.
D、They are unable to rely on muscle contractions to move venous blood from the lower torso to the head.

答案:

B
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[Two-part Analysis]

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题目：

Archaeologist: There were several porcelain-production centers in 18th-century Britain, among them Bristol, Plymouth, and New Hall. Each center developed a unique recipe for its porcelain that might include flint glass, soapstone, bone ash, clay, quartz, and so on. We will therefore be able to determine, on the basis of compositional analysis, where the next cup we recover from this archaeological site was made.

Indicate two different statements as follows: one statement identifies an assumption required by the archaeologist's argument and the other identifies a possible fact that, if true, would, provide significant logical support for the required assumption.

选项:

A、Other cups have been recovered from the archaeological site, all of which were made of porcelain.
B、Some of the cups recovered from the archeological site were not made of porcelain.
C、The next cup to be recovered from the site will likely be made of porcelain.
D、Porcelain makers often traveled between centers, experimenting with one another's recipes.
E、There was considerable overlap of materials in the recipes used by the various centers.
F、Most porcelain in 18th-century Britain was made at one of the several centers.

答案:

C A
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[Data Sufficiency]

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题目：

A department manager distributed a number of pens, pencils, and pads among the staff in the department, with each staff member receiving x pens, y pencils, and z pads. How many staff members were in the department ?
(1)   The numbers of pens, pencils, and pads that each staff member received were in the ratio 2 : 3 : 4, respectively.
(2)   The manager distributed a total of 18 pens, 27 pencils, and 36 pads.

选项:

答案:

E
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[Data Sufficiency]

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题目：

If n is an integer and 2 < n < 6, what is the value of n?
(1)     n is a factor of 15.
(2)     n is a factor of 21.

选项:

答案:

B
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[Reading Comprehension]

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文章：

Line         While the most abundant and dominant species
  within a particular ecosystem is often crucial in
  perpetuating the ecosystem, a “keystone” species,
  here defined as one whose effects are much larger
(5) than would be predicted from its abundance, can
  also play a vital role. But because complex species
  interactions may be involved, identifying a keystone
  species by removing the species and observing
  changes in the ecosystem is problematic. It might
(10) seem that certain traits would clearly define a species
  as a keystone species; for example,
  Pisaster ochraceus is often a keystone predator
  because it consumes and suppresses mussel
  populations, which in the absence of this starfish
(15) can be a dominant species. But such predation on a
  dominant or potentially dominant species occurs in
  systems that do as well as in systems that do not
  have species that play keystone roles. Moreover,
  whereas P. ochraceus occupies an unambiguous
(20) keystone role on wave-exposed rocky headlands,
  in more wave-sheltered habitats the impact of
  P. ochraceus predation is weak or nonexistent,
  and at certain sites sand burial is responsible for
  eliminating mussels. Keystone status appears to
(25) depend on context, whether of particular
  geography or of such factors as community
  diversity (for example, a reduction in species
  diversity may thrust more of the remaining species
  into keystone roles) and length of species
(30) interaction (since newly arrived species in particular
  may dramatically affect ecosystems).


题目：

Which of the following hypothetical experiments most clearly exemplifies the method of identifying species’ roles that the author considers problematic?

选项:

A、A population of seals in an Arctic habitat is counted in order to determine whether it is the dominant species in that ecosystem.
B、A species of fish that is a keystone species in one marine ecosystem is introduced into another marine ecosystem to see whether the species will come to occupy a keystone role.
C、In order to determine whether a species of monkey is a keystone species within a particular ecosystem, the monkeys are removed from that ecosystem and the ecosystem is then studied.
D、Different mountain ecosystems are compared to determine how geography affects a particular species’ ability to dominate its ecosystem.
E、In a grassland experiencing a changing climate, patterns of species extinction are traced in order to evaluate the effect of climate changes on keystone species in that grassland.

答案:

C
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[Undefined]

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Art historian: Unlike many artistic traditions that sought to depict plants native to the local area in a seasonally appropriate way (for example, depicting scenes of spring with the plants in the appropriate stages of development for that season), seventeenth-century Dutch artists specializing in flower paintings almost exclusively chose to depict exotic species of flowers from outside the local area. Painting such species was worthwhile primarily because the art-buying public had developed a strong preference for images of the exotic. The great botanical centers of the time gave the artists direct access to such flowers, which the artists would freely combine in a single painting, regardless of whether the combined species occurred together in the wild, and depicted each in full bloom, regardless of whether those species bloomed at the same time in nature.

Statement: The art historian makes the point that the species of flowers these Dutch artists chose to paint were 1 largely because the species were 2 .

Select for 1 and for 2 the options that complete the statement so that it is most strongly supported by the information provided. Make only two selections, one in each column.
我选的CE，和EC有什么区别？怎么选出EC的？
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An unusually severe winter occurred in Europe after the continent was blanketed by a blue haze resulting from the eruption of the Laki Volcano in the European republic of Iceland in the summer of 1984.  Thus, it is evident that major eruptions cause the atmosphere to become cooler than it would be otherwise.
Which of the following statements, if true, most seriously weakens the argument above?
C选项为什么就不会有张冠李戴的问题呢，1984和1982的气候情况能一样吗，C里的火山就可以试用于原文的火山吗
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[Undefined]

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The rate of a certain chemical reaction is directly proportional to the square of the concentration of chemical A present and inversely proportional to the concentration of chemical B present. If the concentration of chemical B is increased by 100 percent, which of the following is closest to the percent change in the concentration of chemical A required to keep the reaction rate unchanged?
为什么这个题一定是相乘不能是相加呢？y=k1A方-k2B （k1,k2大于0 ），也满足题目说的与A方成正比与B成反比啊？但是这道题只有相乘的情况才能选出正确答案
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[Undefined]

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Tiger beetles are such fast runners that they can capture virtually any nonflying insect.  However, when running toward an insect, the beetles intermittently stop, and then, a moment later, resume their attack.  Perhaps they cannot maintain their pace and must pause for a moment's rest; but an alternative hypothesis is that while running tiger beetles are unable to process the resulting rapidly changing visual information, and so quickly go blind and stop.
 
Which of the following, if discovered in experiments using artificially moved prey insects, would support one of the two hypotheses and undermine the other?
答案C是怎么支持一个猜想又削弱另一个猜想的？
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[GWD]

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The author of the passage implies that which of the following is a possible partial explanation for acquisition behavior during the 1970's and 1980's?
请解释这道题为什么不选C或E，除了正确选项B，我认为文中也正确地提到了这两个选项可以解释acquisition behavior during 1970s and 80s
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[OG]

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The primary purpose of the passage is to
为什么选E不选B
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[Undefined]

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Club X has more than 10 but fewer than 40 members. Sometimes the members sit at tables with 3 members at one table and 4 members at each of the other tables, and sometimes they sit at tables with 3 members at one table and 5 members at each of the other tables. If they sit at tables with 6 members at each table except one and fewer than 6 members at that one table, how many members will be at the table that has fewer than 6 members?
提问小梅老师 这道题求讲一下 我没什么思路 带入数字得的是3
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A photography dealer ordered 60 Model X cameras to be sold for $250 each, which represents a 20 percent markup over the dealer's initial cost for each camera. Of the cameras ordered, 6 were never sold and were returned to the manufacturer for a refund of 50 percent of the dealer's initial cost. What was the dealer's approximate profit or loss as a percent of the dealer's initial cost for the 60 cameras?
请问小梅老师 这道题讲讲一下 我算的是19% 原来成本是200每个 亏了6个 每个亏100. 最后得不出答案
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[Undefined]

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Analytical!
请问may老师，这题该用什么思路来做？
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[Undefined]

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Analytical!
请问张老师，这道题为什么D不对？我有我觉得second paragraph最后一句话特别指向D
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