来自OG11的第二篇阅读，有疑问，请大牛分析一下。

汪寒寒

Although genetic mutations in bacteria and viruses can lead to epidemics, some epidemics are caused by bacteria and viruses that have undergone no significant genetic change. In analyzing the latter, scientists have discovered the importance of social and ecological factors to epidemics. Poliomyelitis, for example, emerged as an epidemic in the United States in the twentieth century by then, modern sanitation was able to delay exposure to polio Until adolescence or adulthood, at which time polio infection produced paralysis. Previously, infection had occurred during infancy, when it typically 9rovided lifelong immunity without paralysis. Thus, the hygiene that helped prevent typhoid epidemics indirectly fostered a paralytic polio epidemic. Another example is lyme disease, which is caused by bacteria that are transmitted by deer ticks. It occurred only sporadically during the late nineteenth century but has recently become prevalent in parts of the United States, largely due to an increase in the deer population that occurred simultaneously with the growth of the suburbs and increased outdoor recreational activities in the deer's habitat. Similarly, an outbreak of dengue hemorrhagic fever became an epidemic in Asia in the 1950's because of ecological changes that caused Aedes aegypti, the mosquito that transmits the dengue virus, to proliferate.The stage is now set in the United States for a dengue epidemic because of the inadvertent introduction and wide dissemination of another mosquito, Aedes albopictus.

最后一题：Which of the following l if true, would most strengthen the author's assertion about the cause of the Lyme disease outbreak in the United States?

(A)The deer population was smaller in the late nineteenth century than in the mid twentieth century.


(B)Interest in outdoor recreation began to grow in the late nineteenth century.

(C)In recent years the suburbs have stopped growing。

(D)Outdoor recreation enthusiasts routinely take measures to protect themselves against Lyme disease.


(E)Scientists have not yet developed a vaccine that can Prevent Lyme disease





我选的E。答案A。问题1：因为我第一感觉是E否定对due to后面削弱，因为如果在文中的recent之时已经有疫苗了，这样人们和鹿虽然说接触了，但肯定不会感染病毒，这样就必然削弱文中给出的因为人和鹿接触的太多而引起的疾病的传播。 但我不知道E为什么错了。问题2：A中mid twentieth century这时间整个文中都貌似没提到，为什么A就可以加强原文？比如说在mid twentieth century之后的十年后是文章写出的时间，那么1在这10年间，鹿的种群出现下降到比the late nineteenth century还少，这样岂不是削弱？
我觉得如果说B不对是因为虽说recreation在the late nineteenth century开始增长，但不知recent是否增长，所以推得B为无关，那么A呢？我想也可以用无关来解释吧。



问题1想通了，E无关。加强的反面可以是无关。