关于OG11第二篇阅读的一个问题

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 provided 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．

有三个原因largely due to

1an increase in the deer population that occurred simultaneously with

2the growth of the suburbs

3and increased outdoor recreational activities in the deer's habitat

B说室内recreation增加，时间对了可是不会 strengthen the author's assertion about the cause of the Lyme disease outbreak in the United States

原文说It occurred only sporadically during the late nineteenth century but has recently become prevalent in parts of the United States，这个recently就是 in the mid twentieth century五十年代后才有GMAT考试的，所以如果A对，就会strengthen the author's assertion

To lukeleng-

Thank you for your reply.

按照你给出的说法，mid twentieth century是我们推断出来的，可是阅读中记得有一条是文章没有提及的概念不要自己来推断。。。

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．

这道题我也曾经做错了，想了很久，后来想明白了B选项的错误如下：

偷换了一个概念，即：recreational activities in the deer's habitat．不等于B选项中的“ outdoor recreation began to grow”

也就是我喜欢去户外玩儿，但是并不一定是去小鹿呆着的地方~~

请指正

right!

嗯，时间误差。。。呵呵，谢谢。

To小鹿和小兵-

谢谢你给出的思路，很明了。

好巧，你的名字里也有小鹿啊^!^文章里也有小鹿。。。