OG-29

jojofgasw

29. The number of people diagnosed as having a certain intestinal disease has dropped significantly in a rural county this year, as compared to last year, Health officials attribute this decrease entirely to improved sanitary conditions at water-treatment plants, which made for cleaner water this year and thus reduced the incidence of the disease.
Which of the following, if true, would most seriously weaken the health officials’ explanation for the lower incidence of the disease?
(A) Many new water-treatment plants have been built in the last five years in the rural county.
(B) Bottled spring water has not been consumed in significantly different quantities by people diagnosed as having the intestinal disease, as compared to people who did not contract the disease.
(C) Because of a new diagnostic technique, many people who until this year would have been diagnosed as having the intestinal disease are now correctly diagnosed as suffering from intestinal ulcers.
(D) Because of medical advances this year, far fewer people who contract the intestinal disease will develop severe cases of the disease.
(E) The water in the rural county was brought up to the sanitary standards of the water in neighboring counties ten years ago.

问题:
1) A也可以理解为削弱? 既然5年前水的条件就改善了, 说明去年和今年,水的条件是相同的, 但结果不同, 说明有别的因素?
2) C的逻辑角度可以理解, 但在理解题意上有些不明白的地方. intestinal ulcers.难道不属于intestinal disease 嘛? C只是说明新技术更准确的判断出是哪种肠道疾病而异.

mary1

(A) Many new water-treatment plants have been built in the last five years in the rural county.
only introduce to readers that there are many new water treatment plants
BUT did not mention anything about the sanitary conditions there, which is the key to weakend the arguments.

and C provides us with an alternative explanation of why increased in sanitary conditions at water plants will not help to decrease the intestinal dieases.