逻辑错题帖~~

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76. Learning how to build a nest plays an important part in the breeding success of birds. For example, Dr. Snow has recorded the success of a number of blackbirds in several successive years. He finds that birds nesting for the first time are less successful in breeding than are older birds, and also less successful than they themselves are a year later. This cannot be a mere matter of size and strength, since blackbirds, like the great majority of birds, are fully grown when they leave the nest. It is difficult to avoid the conclusion that they benefit by their nesting experience.

Which one of the following, if true, would most weaken the argument?

A.        Blackbirds build better nests than other birds.
B.        The capacity of blackbirds to lay viable eggs increase with each successive trial during the first few years of reproduction.
C.        The breeding success of birds nesting for the second time is greater than that of birds nesting for the first time.
D.        Smaller and weaker blackbirds breed just as successfully as bigger and stronger blackbirds.
E.        Up to 25 percent of all birds are killed by predators before they start to nest.

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77. How do the airlines expect to prevent commercial plane crashes? Studies have shown that pilot error contributes to two-thirds of all such crashes. To address this problem, the airline have upgraded their training programs by increasing the hours of classroom instruction and emphasizing communication skills in the cockpit. But it is unrealistic to expect such measures to compensate for pilots’ lack of actual flying time. Therefore, the airlines should rethink their training approach to reducing commercial crashes.

Which one of the following is an assumption upon which the argument depends?

A.        Training programs can eliminate pilot errors.
B.        Commercial pilot routinely undergo additional training throughout their careers.
C.        The number of airline crashes will decrease if pilot training programs focus on increasing actual flying time.
D.        Lack of actual flying time is an important contributor to pilot error in commercial plane crashes.
E.        Communication skills are not important to pilot training programs.

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(A) Training programs can eliminate pilot errors. - It is already stated in the argument. Cannot be an assumption. Argument talks about increasing the training programs. - Incorrect

(B) Commercial pilots routinely undergo additional training throughout their careers. - This is also a given piece of information which can be inferred from the given passage. - Incorrect

(C) The number of airline crashes will decrease if pilot training programs focus on increasing actual flying time. - The use of words like "will" makes it an obvious thing. Focusing on actual flying time may not decrease crashes. - Incorrect

(D) Lack of actual flying time is an important contributor to pilot error in commercial plane crashes. - "Important contributor" states that the lact of actual flying time is one of the contributors for pilor errors. This fills the gap in the argument. Hence this is the assumption - Correct

(E) Communication skills are not important to pilot training programs. - It can be considered to be out of scope - Incorrect

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91. Leachate is a solution, frequently highly contaminated, that develops when water permeates a landifill’s site. If and only if the landfill’s capacity to hold liquids is exceeded does the leachate escape into the environment, generally in unpredictable quantities. A method must be found for disposing of leach ate. Most landfill leachate is sent directly to sewage treatment plants, but not all sewage plants are capable of handling the highly contaminated water.

Which one of the following can be inferred from the passage?

A.        The ability to predict the volume of escaping landfill leachate would help solve the disposal problem.
B.        If any water permeates a landfill, leachate will escape into the environment.
C.        No sewage treatment plants are capable of handling leachate.
D.        Some landfill leachate is sent to sewage treatment plants that are incapable of handling it.
E.        If leachate does not escape from a landfill into the environment, then the landfill’s capacity to hold liquids has not been exceeded.

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此题为充要条件的逆否命题。
A是B的充要条件，那末他的逆否命题比正确！ 非B推出非A

If and only if the landfill’s capacity to hold liquids is exceeded does the leachate escape into the environment, ---------〉If leachate does not escape from a landfill into the environment, then the landfill’s capacity to hold liquids has not been exceeded.

参考答案E
思路：原文说：“Leachate（浸析液）是一种水渗透过垃圾填埋地后生成的溶液，这种溶液通常是高度污染的。当且仅当超出垃圾填埋的容水能力时（A），Leachate会泄露到外界环境中（B）。必须找到一种处理L的方法。许多L被送去用于污水灌溉，但不是所有的污水灌溉的植物都有能力处理这种被高度污染的水”。
原文中If and only if A then B(从B可推出A)；选项E为If not A then not B（非A推非B）正确

A.        原文没有说
B.        条件不对
C.        原文是一部分plants没有这种能力
D.        原文只说明并非所有的污水灌溉的植物都有能力处理这种被高度污染的水，没说some Leachate一定是被送去浇那些无此能力的植物。

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92. Baking for winter holidays is a tradition that may have a sound medical basis. In midwinter, when days are short, many people suffer from a specific type of seasonal depression caused by lack of sunlight. Carbohydrates, both sugars and starches, boost the brain’s levels of serotonin, a neurotransmitter that improves the mood. In this respect, carbohydrates act on the brain in the same way as some antidepressants. Thus, eating holiday cookies may provide an effective form of self-prescribed medication.

Which one of the following can be properly inferred from the passage?

A.        Seasonal depression is one of the most easily treated forms of depression.
B.        Lack of sunlight lowers the level of serotonin in the brain.
C.        People are more likely to be depressed in midwinter than at other times of the year.
D.        Some antidepressants act by changing the brain’s level of serotonin.
E.        Raising the level of neurotransmitters in the brain effectively relieves depression.

xyxyxy_123

yup D should be it...
the passage says that because of lack of sunlight causes depression... but doesnt imply that serotonin levels are lowered...
for instance one can consider this scenario.. depression can be caused by multiple factors X or Y (let x be another element and Y be serotonin)
if X*Y are above a level, the guy is happy... if it receeds below a level the guy gets depressed...
so although Y (serotonin) has remained constant in winter, X could fall to an extent that X*Y is less than the depression line.
and to compensate for the loss of X (which possibly is due to weather conditions and cannot be changed) we are increasing Y to take the score above the depression line..
so B cannot be concluded outright..
D on the other hand says carbohydrates boost the brain’s levels of serotonin, a neurotransmitter that improve the mood.
hence atleast ONE (and in gmat language that is some) antidepressents change the levels of sorotonin.

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Zelda: Dr. Ladlow, a research psychologist, has convincingly demonstrated that his theory about the determinants of rat behavior generates consistently accurate predictions about how rats will perform in a maze. On the basis of this evidence, Dr. Ladlow has claimed that his theory is irrefutably correct.
Anson: Then Dr. Ladlow is not a responsible psychologist, Dr. Ladlow’s evidence does not conclusively prove that his theory is correct. Responsible psychologists always accept the possibility that new evidence will show that their theories are incorrect.

100. Which one of the following can be properly inferred from Anson’s argument?

A.        Dr. Ladlow’s evidence that his theory generates consistently accurate predictions about how rats will perform in a maze is inaccurate.
B.        Psychologists who can derive consistently accurate predictions about how rats will perform in a maze from their theories cannot responsibly conclude that those theories cannot be disproved.
C.        No matter how responsible psychologists are, they can never develop correct theoretical explanations.
D.        Responsible psychologists do not make predictions about how rats will perform in a maze.
E.        Psychologists who accept the possibility that new evidence will show that their theories are incorrect are responsible psychologists.

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Let me give you an outline of how I do this question.
1.        After reading the question, I know that it is an INFERENCE question. I know that the answer is a REQUIRED condition for the conclusion.
2.        Read the argument and understand that the Anson’s conclusion is: Dr. Ladlow is not a responsible psychologist. The premise is: a. research was not conclusive, and b. Responsible psychologists always accept the possibility that new evidence will show that their theories are incorrect.
3.        Read the choices.
a.        Typical wrong answer. It is irrelevant because whether the evidence is accurate or not is not what Anson cares about. It is the conclusiveness of the evidence that he cares about. Whether it is accurate or not, if the two conditions in (2) are met, the doctor is not responsible according to Anson’s argument.
b.        Reads like right answer. It follows both 2a and 2b. Use “not” to test it: Psychologists who can derive consistently accurate predictions about how rats will perform in a maze from their theories CAN responsibly conclude that those theories cannot be disproved. It is a statement that directly counters Anson’s argument. So if Not B is true, Anson’s argument does not hold.
c.        This is another typical wrong answer. It is contrary to what Anson argues. So it cannot be right. Use “not” to test it and I can see that Not C is in accordance with Anson. So C is not right.
d.        D does not follow the reasoning of Anson. Anson does not care about if it is about rats in a maze or birds in a cage. What he cares about is how theories are drawn by psychologists. So D can be removed quickly.
e.        Another typical wrong answer. A  B does not equal to B  A. Basic logic error.

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The brains of identical twins are genetically identical. When only one of a pair of identical twins is a schizophrenic, certain areas of the affected twin’s brain are smaller than corresponding areas in the brain of the unaffected twin. No such differences are found when neither twin is schizophrenic. Therefore, this discovery provides definitive evidence that schizophrenia is caused by damage to the physical structure of the brain.

102. Which one of the following is an assumption required by the argument?

(A) The brain of a person suffering from schizophrenia is smaller than the brain of anyone not suffering from schizophrenia.
(B) The relative smallness of certain parts of the brains of schizophrenics is not the result of schizophrenia or of medications used in its treatment.
(C) The brain of a person with an identical twin is no smaller, on average, than the brain of a person who is not a twin.
(D) When a pair of identical twins both suffer from schizophrenia, their brains are the same size.
(E) People who have an identical twin are no more likely to suffer from schizophrenia than those who do not.