四道逻辑单题看透GRE考试本质——逻辑收敛

先来看看什么是逻辑推理题。

1. 一个程序中现有A、B、C、D、E、F六个语句，但目前这个程序是不协调的，必须删除某些语句才能恢复程序的协调性。已知：

①如果保留语句A，那么必须保留语句B和语句C。

②如果保留语句E，则必须同时删除语句D和语句C。

③如果保留语句E，才能保留语句F。

④语句A是重要的信息，不能删除。

以上各项如果为真，则以下哪一项一定为真：

A. 保留语句E并且删除语句C。

B. 同时保留语句C和语句D。

C. 保留语句E并且删除语句D。

D. 同时删除语句E和语句F。

2. 如果一个人增加每日进餐次数，但不增加进食总量，则他的胆固醇水平会明显下降。然而，大多数人在增加进餐次数的同时也摄入了更多的食物。

如果以上陈述为真，将最有力的支持下面哪一个选项：

A. 在大多数人看来，他每天的进食量不会明显影响他体内的胆固醇水平。

B. 对大多数人来说，增加每天的进食次数，不会使胆固醇水平明显降低。

C. 对大多数人来说，每天的进食量不会受每天的进食次数的影响。

D. 对大多数人来说，进食量受到进食时间的很大影响。

3. 派出所民警讯问公共汽车上的一桩盗窃案的嫌疑人甲、乙、丙、丁的笔录如下：

甲说，反正不是我干的。

乙说，是丁干的。

丙说，是乙干的。

丁说，乙是诬陷。

他们当中只有三人说真话，小偷只有一个是（   ）

4. 某报纸报道，一旅游者不慎落入一平均深度只有0.6m的小河中，溺水身亡。报纸提醒人们旅游时应注意安全，尤其注意地形环境的安全。

以下哪项最能合理的解释报道中的表面性矛盾？

A. 纯属无稽之谈。

B. 该旅游者不足0.6m高。

C. 该旅游者落水点是远远深于小河平均深度的地方。

D. 该旅游者神志不清，如精神分裂等。

5. 在某次网球联赛中，如果甲和乙都没有出线，则丙一定出线。

上述前提中再增加以下哪项，可推出甲出线的结论。

A. 丙出线但乙没有出线。

B. 丙和乙都出线了。

C. 丙和乙都没有出线。

D. 丙没出线但乙出线了。

如果P且Q，那么R
非R推出联言命题为假，那么推出非P或者非Q（相容选言），一真即真，不能全假

以上答案分别为：DB乙CC

但不重要。。

下面的才重要：

Inference 3
Years ago, consumers in Frieland began paying an energy tax in the form of two Frieland pennies for each unit of energy consumed that came from nonrenewable sources. Following the introduction of this energy tax, there was a steady reduction in the total yearly consumption of energy from nonrenewable sources.

 

1. If the statements in the passage are true, then which of the following must on the basis of them be true?

A. There was a steady decline in the yearly revenues generated by the energy tax in Frieland.

B. There was a steady decline in the total amount of energy consumed each year in Frieland.

C. There was a steady increase in the use of renewable energy source in Frieland.

D. The revenues generated by the energy tax were used to promote the use of energy from renewable sources.

E. The use of renewable energy sources in Frieland greatly increased relative to the use of nonrenewable energy sources.

Inference 1

A ten-year comparison between the United States and the Soviet Union in terms of crop yields per acre revealed that when only planted acreage is compared, Soviet yields were equal to 68 percent of United States yields. When total agricultural acreage (planted acreage plus fallow acreage) is compared, however, Soviet yield was 114 percent of United States yield.

 

2. From the information above, which of the following can be most reliably inferred about United States and Soviet agriculture during the ten-year period?

A. A higher percentage of total agricultural acreage was fallow in the United States than in the Soviet Union.

B. The United States had more fallow acreage than planted acreage.

C. Fewer total acres of available agricultural land were fallow in the Soviet Union than in the United States.

D. The Soviet Union had more planted acreage than fallow acreage.

E. The Soviet Union produced a greater volume of crops than the United States produced.

Inference 2 ASSUMPTION
New methods developed in genetic research have led taxonomists to revise their views on the evolutionary relationships between many species. Traditionally the relatedness of species has been ascertained by a close comparison of their anatomy. The new methods infer the closeness of any two species’ relationship to each other directly from similarities between the species’ genetic codes.

3. Which of the following conclusions is best supported by the information?

A. The apparent degree of relatedness of some species, as determined by anatomical criteria, is not borne out by their degree of genetic similarity.

B. When they know the differences between two species’ genetic codes, taxonomists can infer what the observable anatomical differences between those species must be.

C. The degree to which individuals of the same species are anatomically similar is determined more by their genetic codes than by such environmental factors as food supply.

D. The traditional anatomical methods by which taxonomists investigated the relatedness of species are incapable of any further refinement.

E. Without the use of genetic methods, taxonomists would never be able to obtain any accurate information about species’ degrees of relatedness to one another.

Inference 4

Normally, seeds of Emmenathe penduliflora stay dormant for years and germinate only when a fire burns through their habitat. Nitrogen dioxide in the smoke induces the seeds to germinate. Fires clear the bush, allowing germinating seeds to receive the sunlight they need to grow. The plants mature quickly, produce seeds, and then die. In areas with heavy automobile traffic, however, the seed germinates in the absence of fire, with automobile exhaust supplying the required nitrogen dioxide.

 

4. The information given, if accurate, most strongly supports which of the following hypotheses?

A. Fires in the habitat of E. penduliflora do not entirely destroy the plant's seeds even in the places where the fires burn most intensely.

B. The nitrogen dioxide in automobile exhaust cannot harm plants of E. penduliflora after germination.

C. If human intervention decreases the number of fires in the habitat of E. penduliflora, automobile exhaust can replicate the conditions the plant requires in order to thrive.

D. Within the habitat of E. penduliflora, natural fires are significantly more frequent in areas with heavy automobile traffic than they are in other areas.

E. Unless E. penduliflora seeds that have germinated can survive in the shade, automobile exhaust threatens the long-term survival of the plant in areas with heavy automobile traffic.

以上答案为：AAAE