4. Reviewing historical data, medical researchers in LACE w:st="on">CaliforniaLACE> found that counties with the largest number of television sets per capita have had the lowest incidence of a serious brain disease, mosquito-borne encephalitis. The researchers have concluded that people in these counties stay indoors more and thus avoid exposure to the disease.

The researchers’ conclusion would be most strengthened if which of the following were true?

(A) Programs designed to control the size of disease-bearing mosquito populations have not affected the incidence of mosquito borne encephalitis.

(B) The occupations of county residents affect their risk of exposure to mosquito-borne encephalitis more than does television-watching.

(C) The incidence of mosquito-borne encephalitis in counties with the largest number of television sets per capita is likely to decrease even further.

(D) The more time people in a county spend outdoors, the greater their awareness of the dangers of mosquito-borne encephalitis.（E）

(E) The more television sets there are per capita in a county, the more time the average county resident spends watching television.

E. 没有问题.加强。

我想问A. 我觉得A貌似排除它因的加强. 判断其错的原因是不是因为affect. 并没有明确指出是怎么影响发病率的(是使其增加还是减少) 所以,A对结论没有作用..

我的理解对吗?

I agree. The conclusion links the number of TV sets with the reason for low brain disease incidence. A doesn't help because it talked about what doesn't affect the disease rate, not what does.

原文是对人均电视不同的国家的E发病率的比较。A错在没指明是人均电视占有率高的，还是低的国家的情况。控制携带病菌的蚊子数量，如果起作用，当然是减少发病率，不会是增加发病率。所以你的理由不成立。如果A改为 Programs designed to control the size of disease-bearing mosquito populations in coutries with the largest number of television sets per capita have not affected the incidence of mosquito borne encephalitis