【每日逻辑练习第二季】【1-1】

daisyの小夢想

在我们CR小分队的共同努力和老大的鼎力支持下，每日逻辑练习终于完成了改进工作，我们都小激动了一翻。
正如我们的序言所言，“坚持梦，做更好的CR”，每日逻辑练习追求的是不断进步，不断成长为更好的练习模式。
所以，非常期待广大XDJM们一起练习、一起钻研，用共同的脑力结晶创造更好的CR!


跟帖做题方法请见：
http://forum.chasedream.com/GMAT_CR/thread-613902-1-1.html





【精练】
1. Carl is clearly an incompetent detective. He has
solved a smaller percentage of the cases assigned to
him in the last 3 years—only 1 out of 25—than any
other detective on the police force.
Which one of the following, if true, most seriously
weakens the argument above?
--BIBLE WEAKEN NO.1
(A) Because the police chief regards Carl as the
most capable detective, she assigns him only
the most difficult cases, ones that others have
failed to solve.
(B) Before he became a detective, Carl was a
neighborhood police officer and was highly
respected by the residents of the
neighborhood he patrolled.
(C) Detectives on the police force on which Carl
serves are provided with extensive resources,
including the use of a large computer
database, to help them solve crimes.
(D) Carl was previously a detective in a police
department in another city, and in the 4 years
he spent there, he solved only 1 out of 30
crimes.
(E) Many of the officers in the police department in
which Carl serves were hired or promoted
within the last 5 years.





【逻辑链】
2.
Although fullerenes--spherical molecules made entirely of carbon--were first found in the laboratory, they have since been found in nature, formed in fissures of the rare mineral shungite.  Since laboratory synthesis of fullerenes requires distinctive conditions of temperature and pressure, this discovery should give geologists a test case for evaluating hypotheses about the state of the Earth's crust at the time these naturally occurring fullerenes were formed.


Which of the following, if true, most seriously undermines the argument?
--PREP07 CR1 NO.1

(A) Confirming that the shungite genuinely contained fullerenes took careful experimentation.
(B) Some fullerenes have also been found on the remains of a small meteorite that collided with a spacecraft.
(C) The mineral shungite itself contains large amounts of carbon, from which the fullerenes apparently formed.
(D) The naturally occurring fullerenes are arranged in a previously unknown crystalline structure.
(E) Shungite itself is formed only under distinctive conditions.





3.
Economist:  On average, the emergency treatment for an elderly person for injuries resulting from a fall costs $11,000.  A new therapeutic program can significantly reduce an elderly person's chances of falling.  Though obviously desirable for many reasons, this treatment program will cost $12,500 and thus cannot be justified.


Which of the following, if true, most seriously undermines the conclusion of the argument?
--PREP07 CR1 NO.2

(A) Among elderly people who had followed the program for only a few months, the number of serious falls reported was higher than it was for people who had followed the program for its recommended minimum length of one year.
(B) Falls resulting in serious injuries are less common among elderly people living in nursing homes than they are among elderly people who live alone at home.
(C) A frequent result of injuries sustained in falls is long-term pain, medication for which is not counted among the average per-person costs of emergency treatment for elderly people's injuries from such falls.
(D) The new therapeutic program focuses on therapies other than medication, since overmedication can cause disorientation and hence increase the likelihood that an elderly person will have a serious fall.
(E) A significant portion of the cost of the new therapeutic program is represented by regular visits by health care professionals, the costs of which tend to increase more rapidly than do those of other elements of the program.


4.
The prairie vole, a small North American grassland rodent, breeds year-round, and a group of voles living together consists primarily of an extended family, often including two or more litters.  Voles commonly live in large groups from late autumn through winter; from spring through early autumn, however, most voles live in far smaller groups.  The seasonal variation in group size can probably be explained by a seasonal variation in mortality among young voles.


Which of the following, if true, provides the strongest support for the explanation offered?
--PREP07 CR1 NO.3

(A) It is in the spring and early summer that prairie vole communities generally contain the highest proportion of young voles.
(B) Prairie vole populations vary dramatically in size from year to year.
(C) The prairie vole subsists primarily on broad-leaved plants that are abundant only in spring.
(D) Winters in the prairie voles' habitat are often harsh, with temperatures that drop well below freezing.
(E) Snakes, a major predator of young prairie voles, are active only from spring through early autumn.


5.
A popular beach has long had a dolphin feeding program in which fish are given to dolphins several times a day; many dolphins get as much as half of their food each day there.  Although dolphins that first benefit from the program as adults are healthy and long-lived, their offspring have a lower life expectancy than offspring of dolphins that feed exclusively in the wild.


Which of the following, if true, most helps to explain the lower life expectancy of offspring of dolphins feeding at the beach compared to other young dolphins?
--PREP07 CR1 NO.4

(A) Sharks that prey on dolphins are less common in the open seas off the beach than in many other areas of the open seas where dolphins congregate.
(B) Many of the adult dolphins that feed at the beach are females that nurse their offspring there.
(C) The fish given to the dolphins at the beach are the same types of fish that dolphins typically catch in the wild.
(D) Many dolphins that feed at the beach with their offspring come to the beach only a few times a month.
(E) Adult dolphins that feed at the beach spend much less time teaching their offspring how to catch fish in the wild than do other adult dolphins.

daisyの小夢想

Key:(答案藏在此哦哈)
A DCEE

【精练题解释】
Answer choice (A): This is the correct answer. We discover that Carl receives
the hardest cases, and one would expect that the hardest cases would yield a
lower success rate. Notice that this answer does not attack the premises. Even
though they are still true, the conclusion is undermined by the new evidence.
This is typical of most Weaken questions answers—the premises are not
addressed and the focus is on the conclusion.

Answer choice (B): This answer is irrelevant. It tries to use the opinion of others
about Carl’s performance in one capacity to refute facts about his performance
in another capacity. Personalize the answer—is this the answer you would offer
to weaken the argument against Carl if he was your friend?

Answer choice (C): This is an Opposite answer that strengthens the claim that
Carl is incompetent by showing that Carl was not deprived of certain resources
for solving cases.

Answer choice (D): This is another Opposite answer that strengthens the claim
that Carl is incompetent. This time, the answer shows that Carl has a previous
record of poor performance.

Answer choice (E): This answer goes beyond the scope of the argument by
discussing the promotions of other officers. These promotions do not impact
Carl’s job and no information is given about Carl’s promotions. If you are
thinking that perhaps Carl’s poor performance is a result of dissatisfaction over
the promotions of others, then you are assuming too much.

xeyyxzty

1. premise: He has solved a smaller percentage of the cases assigned to him in the last 3 years—only 1 out of 25—than any other detective on the police force.
conclusion: Carl is clearly an incompetent detective.
cases assigned to him--what cases???
A--right
B--irrelevant--the conclusion is an incompetent detective, not a police officer
C,D--support
E--irrelevant--both in 5 years and promoted
2.background information: Although fullerenes--spherical molecules made entirely of carbon--were first found in the laboratory, they have since been found in nature, formed in fissures of the rare mineral shungite.  premise: Since laboratory synthesis of fullerenes requires distinctive conditions of temperature and pressure,conclusion: this discovery should give geologists a test case for evaluating hypotheses about the state of the Earth's crust at the time these naturally occurring fullerenes were formed.

maybe the formation in labs is different from that in nature.
A,C,D,E--irrelevant...不对吧~可是不知道呀
B--right
3.background information:On average, the emergency treatment for an elderly person for injuries resulting from a fall costs $11,000.  A new therapeutic program can significantly reduce an elderly person's chances of falling.  
premise: this treatment program will cost $12,500
conclusion: thus cannot be justified
it depends on the number of the falling ( in my point of view, the falling costs will exceed the cost of the program in some day )
A,B--irrelevant
C--right
D,E--support
4.background information: The prairie vole, a small North American grassland rodent, breeds year-round, and a group of voles living together consists primarily of an extended family, often including two or more litters.  
premise:Voles commonly live in large groups from late autumn through winter; from spring through early autumn, however, most voles live in far smaller groups.
conclusion:the seasonal variation in group size can probably be explained by a seasonal variation in mortality among young voles.
the young may live with their family in autumn and winter but leave when spring comes.
A--weaken
B--the effect is uncertain
C--irrelevant? i don't know
D--irrelevant
E--right--i'm not sure
这个猜测猜错了~breeds year round是需要哺乳一年吧~
5.premise:A popular beach has long had a dolphin feeding program in which fish are given to dolphins several times a day; many dolphins get as much as half of their food each day there.
conclusion:dolphins that first benefit from the program as adults are healthy and long-lived, their offspring have a lower life expectancy than offspring of dolphins that feed exclusively in the wild.
the difference between the long-lived and the short-lived: resources of food when they are young~that's the point
A--weaken
B,C,D--irrelevant
E--right
第一次回逻辑贴~不知道怎么回呀~
还有时间有些慢~不报时间了
也不知道做的对不对~不好意思了

fox0923

我站位~~先看看CR怎么回再说---看好了，过来发帖~


精练--20s--Weaken
Premise：Carl only solve 1 out of 25 cases in the past 3 years.
Conclusion: Carl is incompetent detective.
Prephrase: 1 out of 25 cases can be the most difficult case Carl has been dealing with.
Analysis:
(A) Because the police chief regards Carl as the
most capable detective, she assigns him only
the most difficult cases, ones that others have
failed to solve.
---------------------------------------------------------correct. this choice brings new info. to identify the specialty of the cases that Carl dealt with is different from other detectives'.

(B) Before he became a detective, Carl was a
neighborhood police officer and was highly
respected by the residents of the
neighborhood he patrolled.
--------------------------------------------------------what position Carl used to be is irrelevant with the cases he's currently dealing with.

(C) Detectives on the police force on which Carl
serves are provided with extensive resources,
including the use of a large computer
database, to help them solve crimes.
-----------------------------------------------------------If the external resources can provide better service to improve the efficiency of cases, then this is to support the argument that Carl is not a good detective.

(D) Carl was previously a detective in a police
department in another city, and in the 4 years
he spent there, he solved only 1 out of 30
crimes.
---------------------------------------------------------- this kinda restate the premise in the argument, this will not help to weaken the conclusion at all.

(E) Many of the officers in the police department in
which Carl serves were hired or promoted
within the last 5 years.
---------------------------------------------------------------Other officers' promotion changes are irrelevant with Carl, if there's anything, this choice supports the conclusion by inferring Carl is not promoted yet.


不知道这么分析行不行，准备精练题目就这么分析，然后下面的练习题目就稍微在选项的解释上活分一些。等待我们家版主纠正

南瓜0729

嘿嘿 我分析的好像有点简短 明天仔细一点1.15s
P：C solved a smaller percentage of the cases
C: C is an incompetent detective
P: C solved the most difficult cases.
A
A right answer
B irrelevant
C strengthen
D strengthen
E irrelevant


2.36s
B:F were found in nature, formed in rare substance.
P:lab synthesis of F requires distinctive conditions
C: the discovery can help evaluate hypotheses about state of the Earth's crust.
P:something hinders the analysis of the state of the Earth's crust
D


3.33s
p: Previous treatment costs 11000. A new one costs 12500 and it can reduce the chance of falling
C: it cannot be justified.
P: 以前治疗之后经常复发，新的不会
C


4.34s
P：autumn-winter V live in a larger group than they do in spring- summer
C: this happens because of the seasonal variation in mortality
P: in spring-summer, V have smaller amount of food.
E


5.25s
B：a beach has a feeding program. dolphins get half of the food there.
P: they benefit at first.
C: their offspring have a lower life expectancy.
P: their offspring 捕食能力差
E

daisyの小夢想

我站位~~先看看CR怎么回再说

-- by 会员 fox0923 (2011/11/19 22:26:41)

 糊糊 糊糊之前写的已经是超级模范了 >,<

phoebe0624

我滚过来补作业了！
1、精炼题
Premise:He has solved cases assigned than any other detective on the police force.
Conclusion:Carl is clearly an incompetent detective
Q:weaken
Analysis:
A-because he is a good detective, so his cases are so difficult to deal with.  (他因削弱）
B-irrelevant
C- strengthen
D- strengthen
E-irrelevant

2、逻辑链
Premise:He has solved cases assigned than any other detective on the police force.
Conclusion:Carl is clearly an incompetent detective

chensong211

精炼题：
Premise: he solved s smaller percentage of the cases.
Conclusion: carl is incompetent detective.
Conclusion: carl is incompetent detective.
推测Weaken: case难度大，都是疑难杂按。
逻辑思路：案件办理的少=/= 办案能力低，不胜任detective
A) Because the police chief regards Carl as the
most capable detective, she assigns him only
the most difficult cases, ones that others have
failed to solve.正确
(B) Before he became a detective, Carl was a无关选项，没有提及case
neighborhood police officer and was highly
respected by the residents of the
neighborhood he patrolled.
(C) Detectives on the police force on which Carl无关没有提及case
serves are provided with extensive resources,
including the use of a large computer
database, to help them solve crimes.
(D) Carl was previously a detective in a police加强。
department in another city, and in the 4 years
he spent there, he solved only 1 out of 30
crimes.
(E) Many of the officers in the police department in无关没有提及case
which Carl serves were hired or promoted
within the last 5 years.


第二题
Premise: laboratory made the fullerenes
Conclusion: geologists can evaluate the state of the Earth’s crust.
Weaken: 满足制造fullerens的条件不能预测Earth’s crust，还会有其他条件。即：多种条件导致Earth’s crust
第二题也不太确定。应该选D吧。

第三题：
Premise:A new program can reduce chances of falling.

Conclusion: this treatment program will cost $12500 and thus cannot be justified.

Logic: 1.this program will not cost $12500 we can justify the cost.

第二题.we can confuse the new program.
A.bingo
B.无关。
C.加强，说摔倒要花更多的钱。
D.间接的削弱，这个不直接，所以pass了。
E.加强。
第三题：
Premise:A new program can reduce chances of falling.

Conclusion: this treatment program will cost $12500 and thus cannot be justified.

Logic: 1.this program will not cost $12500 we can justify the cost.

2.we can confuse the new program.
A直接否定New program 正确
B.无关

C.加强

D.间接否定不能选

E.加强


第四题：
Premise：voles live in large groups from late autumn through winter, live in smaller groups from spring through early autumn.
Conclusion：the mortality among young voles can explain the seasonal variation in group.
Logic: because the cold/food, the voles dead, they are together form late autumn through winter.
A.提到young voles 但是时间段the spring and early summer 不对。Pass
B.无关。
C.spring食物丰富，时间段不对。
D.时间点没有严格对应 late atumn 没有E严格。
E.bingo 时间完全对应。简单推断也向到mortality，所以选E
要根据常识，应该选D，因为冬天冷，动物群居。但是做逻辑题，我认为要把自己当白痴，什么常识都没有，只能通过题目给的信息判断。所以E更加合适。
第五题
Premise: the feeding program, the adult dolphins are healthy and long-lived.

Conclusion: their offspring have a lower life expectancy than offspring of dolphins that feed exclusively in the wild.
logic: the feeding program is harmful for dolphin.

A.没有提及后代，岸边海豚与野生海豚的比较。

B.无关。

C.没有明确指出喂一种鱼危害后代健康。

D.无关。

E. bingo 提到后代，及对后代的危害。

我逻辑刚刚开始做，跟着小分队突击。
时间嘛，很长。这里就不说了。
我做题的体会：1.核心对象2.时间点3.动词
这三个最好都对应，选项完美，如果没有那就选最全的。
还有，把自己当白痴，什么都不懂任何常识都没有，去做逻辑。
这是我的一点点心得，不对的地方请大家指正。谢谢。

fox0923

精炼题：
Premise: he solved s smaller percentage of the cases.
Conclusion: carl is incompetent detective.
Conclusion: carl is incompetent detective.

Weaken:case难度大，都是疑难杂按。
逻辑思路：案件办理的少=/= 办案能力低，不胜任detective
第二题
Premise: laboratory made the fullerenes
Conclusion: geologists can evaluate the state of the Earth’s crust.
Weaken: 满足制造fullerens的条件不能预测Earth’s crust，还会有其他条件。即：多种条件导致Earth’s crust

第一次回逻辑贴，是这样分析吗？而且没有选项啊。谁能告诉我。谢谢

-- by 会员 chensong211 (2011/11/19 23:57:03)

选项是白色字体，chensong用鼠标在每道题的下面drag一下就可以看到了~

fox0923

我站位~~先看看CR怎么回再说

-- by 会员 fox0923 (2011/11/19 22:26:41)

 糊糊 糊糊之前写的已经是超级模范了 >,<

-- by 会员 daisyの小夢想 (2011/11/19 22:40:05)

嘻嘻~还是要回去看一下，毕竟和之前的逻辑链不一样，还是细致点好！