问答

1答疑

[Reading Comprehension]

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文章：

    More selective than most chemical pesticides in that they ordinarily destroy only unwanted species, biocontrol. agents (such as insects, fungi, and( viruses) eat, infect, or parasitize targeted plant or animal pests. However, biocontrol agents can negatively affect nontarget species by, for example, competing with them for resources: a biocontrol agent might reduce the benefits conferred by a desirable animal species by consuming a plant on which the animal prefers to lay its eggs. Another example of indirect negative. consequcnces occurred in England when a virus introduced to control rabbits reduced the amount of open ground (because large rabbit populations reduce the ground cover), in turn reducing underground ant nests and triggering the extinction of a blue butterfly that had depended on the nests to shelter its offspring. The paucity of known extinctions or disruptions resulting from indirect interactions may reflect not the infrequency of such mishaps but rather the failure to look for or to detect them: most organisms likely to be adversely affected by indirect interactions are of little or no known commercial value and the events linking a biocontrol agent with an adverse effect are often unclear. Moreover, determining the potential risks of biocontrol agents before they are used is difficult, especially when a nonnative agent is introduced, because, unlike a chemical pesticide, a biocontrol agent may adapt in unpredictable ways. so that it can feed on or otherwise harm new hosts.

题目：

The passage is primarily concerned with

选项:

A、explaining why until recently scientists failed to recognize the risks presented by biocontrol agents.
B、emphasizing that biocontrol agents and chemical pesticides have more similarties than differences.
C、suggesting that only certain biocontrol agents should be used to control plant or animal pasts.
D、arguing that biocontrol agents involve risks, some of which may not be readily discerned.
E、suggesting that mishaps involving biocon-troll agents are relatively commonplace.

答案:

D
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[Problem Solving]

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题目：

The graph of which of the following equations is a straight line that is parallel to line l in the figure above?

选项:

A、3y-2x = 0
B、3y+2x = 0
C、3y+2x = 6
D、2y-3x = 6
E、2y+3x = -6

答案:

A
1答疑

[Critical Reasoning]

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题目：

The first African slaves were brought to the Americas in the early 1600s, where their labor was used primarily for agricultural and household purposes. The institution of slavery in the New World presupposes not only the existence of slaves and owners, but also a system of laws in place which recognized and protected the practice of slavery. However, laws were not enacted, for example, declaring slaves the personal property of their owners and imposing punishments upon those who aided slaves in escape, until many years later.
If the sentences in the passage above are true, then they support which one of the following statements? 

选项:

A、A. Arguing that laws needed to be enacted recognizing and protecting the institution of slavery before the practice of slavery could have existed in the New World is to ignore historical fact.
B、B. Prior to 1700, some of the Europeans who came to the New World enslaved native Indian populations.
C、C. Slavery was practiced in many parts of the world before Africans were first brought to the New World as slaves.
D、D. The prior existence of a supportive legal system is needed before an institutional practice can develop.
E、E. One of the reasons slavery developed in the New World was the tremendous need for manual labor.

答案:

A
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[Problem Solving]

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题目：

Working simultaneously and independently at an identical constant rate, 4 machines of a certain type can produce a total of x  units of product P  in 6 days. How many of these machines, working simultaneously and independently at this constant rate, can produce a total of 3x  units of product P  in 4 days?

选项:

A、24
B、18
C、16
D、12
E、8

答案:

B
1答疑

[Data Sufficiency]

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题目：

选项:

A、Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B、Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C、BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D、EACH statement ALONE is sufficient.
E、Statements (1) and (2) TOGETHER are NOT sufficient.

答案:

D
1答疑

[Reading Comprehension]

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文章：

Line         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
(5) 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
(10) 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
(15) 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
(20) 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
(25) 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
(30) 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
(35) 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
(40) 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
(45) apparently improve the flow of venous blood
  returning to the heart.


题目：

The passage provides information in support of which of the following assertions?

选项:

A、The disadvantages of an adaptation to a particular feature of an environment often outweigh the advantages of such an adaptation.
B、An organism’s reaction to being placed in an environment to which it is not well adapted can sometimes illustrate the problems that have been solved by the adaptations of organisms indigenous to that environment.
C、The effectiveness of an organism’s adaptation to a particular feature of its environment can only be evaluated by examining the effectiveness with which organisms of other species have adapted to a similar feature of a different environment.
D、Organisms of the same species that inhabit strikingly different environments will often adapt in remarkably similar ways to the few features of those environments that are common.
E、Different species of organisms living in the same environment will seldom adapt to features of that environment in the same way.

答案:

B
1答疑

[Data Sufficiency]

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题目：

选项:

A、Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B、Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C、BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D、EACH statement ALONE is sufficient.
E、Statements (1) and (2) TOGETHER are NOT sufficient.

答案:

C
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[Critical Reasoning]

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题目：

Plan: Concerned about the welfare of its senior citizens, the government of Runagia decided two years ago to increase by 20 percent the government-provided pension paid to all Runagians age sixty-five and older. Result: Many Runagian senior citizens are no better off financially now than they were before the increase. Further information: The annual rate of inflation since the pension increase has been below 5 percent, and the increased pension has been duly received by all eligible Runagians.

In light of the further information, which of the following, if true, does most to explain the result that followed implementation of the plan?

选项:

A、The majority of senior citizens whose financial position has not improved rely entirely on the government pension for their income.
B、The Runagian banking system is so inefficient that cashing a pension check can take as much as three weeks.
C、The prices of goods and services that meet the special needs of many senior citizens have increased at a rate much higher than the rate of inflation.
D、The pension increase occurred at a time when the number of Runagians age sixty-five and older who were living below the poverty level was at an all-time high.
E、The most recent pension increase was only the second such increase in the last ten years.

答案:

C
1答疑

[Reading Comprehension]

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文章：

Line         Biologists have advanced two theories to explain
  why schooling of fish occurs in so many fish species.
  Because schooling is particularly widespread among
  species of small fish, both theories assume that
(5) schooling offers the advantage of some protection
  from predators.
       Proponents of theory A dispute the assumption
  that a school of thousands of fish is highly visible.
  Experiments have shown that any fish can be seen,
(10) even in very clear water, only within a sphere of 200
  meters in diameter. When fish are in a compact group,
  the spheres of visibility overlap. Thus the chance of
  a predator finding the school is only slightly greater
  than the chance of the predator finding a single fish
(15) swimming alone. Schooling is advantageous to the
  individual fish because a predator’s chance of finding
  any particular fish swimming in the school is much
  smaller than its chance of finding at least one of
  the same group of fish if the fish were dispersed
(20) throughout an area.
       However, critics of theory A point out that some
  fish form schools even in areas where predators
  are abundant and thus little possibility of escaping
  detection exists. They argue that the school continues
(25) to be of value to its members even after detection.
  They advocate theory B, the “confusion effect,” which
  can be explained in two different ways.
       Sometimes, proponents argue, predators simply
  cannot decide which fish to attack. This indecision
(30) supposedly results from a predator’s preference
  for striking prey that is distinct from the rest of the
  school in appearance. In many schools the fish are
  almost identical in appearance, making it difficult for a
  predator to select one. The second explanation for
(35) the “confusion effect” has to do with the sensory
  confusion caused by a large number of prey moving
  around the predator. Even if the predator
  makes the decision to attack a particular fish,
  the movement of other prey in the school can
(40) be distracting. The predator’s difficulty can
  be compared to that of a tennis player trying
  to hit a tennis ball when two are approaching
  simultaneously.


题目：

According to the passage, both theory A and theory B have been developed to explain how

选项:

A、fish hide from predators by forming schools
B、forming schools functions to protect fish from predators
C、schooling among fish differs from other protective behaviors
D、small fish are able to make rapid decisions
E、small fish are able to survive in an environment densely populated by large predators

答案:

B
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[Data Sufficiency]

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题目：

Are at least 10 percent of the people in Country X who are 65 years old or older employed?
(1) In Country X, 11.3 percent of the population is 65 years old or older.
(2) In Country X, of the population 65 years old or older, 20 percent of the men and 10 percent of the women are employed.

选项:

A、Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B、Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C、BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D、EACH statement ALONE is sufficient.
E、Statements (1) and (2) TOGETHER are NOT sufficient.

答案:

B
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1933浏览

[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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5024浏览

[Undefined]

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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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5707浏览

[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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1912浏览

[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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4131浏览

[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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2898浏览

[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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1915浏览

[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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2003浏览

[Undefined]

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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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427239浏览

[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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434377浏览

[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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