请帮忙看看：lsat test2 II 17-23

愉悦

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17）The advanced technology of ski boots and bindings has brought a dramatic drop in the incidence of injuries that occur on the slopes of ski resorts: from 9 injuries per 1,000 skiers in 1950 to 3 in 1980. As a result, the remainder of ski-related injuries, which includes all injuries occurring on the premises of a ski resort but not on the slopes, rose from 10 percent of all ski-related injuries in 1950 to 25 percent in 1980. The incidence of these injuries, including accidents such as falling down steps, increases with the amount of alcohol consumed per skier.

. Which one of the following conflicts with information in the passage?

(A) The number of ski injuries that occurred on the slopes was greater in 1980 than in 1950.

(B) A skier was less likely to be injured on the slopes in 1950 than in 1980.

(C) The reporting of ski injuries became more accurate between 1950 and 1980.

(D) The total number of skiers dropped between 1950 and 1980.

(E) Some ski-related injuries occurred in 1980 to people who were not skiing

此题 （D）为何不对？ （B）就是正确答案？

23）Despite improvements in treatment for asthma, the death rate form 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.

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

(A) Urban pollution has not doubled in the past decade.

(B) Doctors and patients generally ignore the role of allergies in asthma.

(C) Bronchial inhalers are unsafe, even when used according to the recommended instructions.

(D) The use of bronchial inhalers aggravates other diseases that frequently occur among asthma sufferers and that often lead to fatal outcomes even when the asthma itself does not.

(E) Increased urban pollution, improved recording of asthma deaths, and the use of bronchial inhalers are the only possible explanations of the increased death rate due to asthma.

我看(D), (E) 都可能对， 这种情况如何取舍？

justag

17

The trick of such problems lies in the difference between "absolute no." and "relative rate". Although the passage addressed "incidence", it only quoted the relative rate "9 injuries on slopes per 1000","10 percent" etc. So it's safe to understand it from the "rate" point of view. Accordingly, choices mentioning total no. of injuries or sth. may or may not conflict with the passage, yet B, the rate, is just opposite to the statement "from 9 injuries per 1,000 skiers in 1950 to 3 in 1980"

23

choose the most direct one, or "take the opposite of the confusing choice" and see if you can still draw the conclusion. If not, the confusing one should be the assumption.

one reason...the second reason... Now that the second reason is invalid, it must be inhalers (the third reason). E is the assumption yet D is just the effects of the inhalers (the third reason).

愉悦

谢谢！我明白了。