4. 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.

　　参考答案：B

　　思路：结论：How to build a nest is very important.第一句话。论据：birds nesting ,不如老bird success, also less than 。。。其实就一句话，新birds没用经验nesting,所以生育成功率低。

　　削弱方向：

　　1、断桥，论据与结论无关，即新birds nesting。。 推不出how to build a nest plays an important part in the breeding success of birds.

　　2、他因：有其他的原因可以解释论据。

　　3、驳斥论据的有效性;

　　A. 无关，比较点不对，和其他bird无关

　　B. 他因，success 是与capacity 有关。

　　C. 无关，陷阱，把论据重新说呢一遍。The breeding success of birds nesting for the second time is greater than that of birds nesting for the first time.= 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.

　　D. 无关，文中没有比较smaller ,weaker。Smaller, weaker birds 完全有可能知道 how to build a nest .

　　E. 无关，birds被杀和breeding success of birds 无关，如果是出生(breeding)的birds 被杀就有关了。

　　评论：排除法是最有效的，因为不正确选项简单。而正确选项的推理过程有点扰。

　　5. 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.

　　参考答案：D

　　思路：xxx的program 不能补充pilots’ lack of actual flying time.结论：thererfore, rethink approach to prevent commercial plane crash. 中间有思维跳跃，actual flying time 与plane crash 什么关系?

　　A. 削弱，program can eliminate…, so do not need rethink approach

　　B. 无关。题中是prevent planes crashes的training.

　　C. 加强。

　　D. 将actual flying time 与(pilot error in) plane crashes 联系起来。对assumption取非：actual flying time is not an important contributor to pilot error in commercial plane crashes. 削弱结论。符合ETS假设定义。

　　E. 加强。

　　评论：比较简单，不要关心废话。

　　Questions 6-7

　　Despite improvements in treatment for asthma, the death rate from this disease has doubled during the past decade from its previous rate. Two possible explanations for this increase have been offered. First, the recording of deaths due to asthma has become more widespread and accurate in the past decade than it had been previously. Second, there has been an increase in urban pollution. However, since the rate of deaths due to asthma has increased dramatically even in cities with long-standing, comprehensive medical records and with little or no urban pollution, one must instead conclude that the cause of increased deaths is the use of bronchial inhalers by asthma sufferers to relieve their symptoms.

　　6. Each of the following, if true, provides support to the argument EXCEPT:

　　A. Urban populations have doubled in the past decade.

　　B. Records of asthma deaths are as accurate for the past twenty years as for the past ten years.

　　C. Evidence suggests that inhalers make the lungs more sensitive to irritation by airborne pollen.

　　D. By temporarily relieving the symptoms of asthma, inhalers encourage sufferers to avoid more beneficial measures.

　　E. Ten years ago bronchial inhalers were not available as an asthma treatment.

　　参考答案：A

　　思路：现象：death rate doubled. 结论：the cause of increased death is ……

　　支持方向：

　　1，论据的有效性。

　　2，的确是这个原因。

　　A. 削弱, 人口double了，支持了two possible explanations之一，反对了结论。

　　B. 支持。中心，过去，现在一样accurate.

　　C. 支持结论，就是inhalers 造成的。

　　D. 同C。

　　E. 支持，排除可以削弱的他因(eg, Ten years ago bronchial inhalers were as many as that used today. 就是削弱)。