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
(5) discovered the importance of social and ecological fac-
tors to epidemics. Poliomyelitis, for example, emerged
as an epidemic in the
century; by then, modern sanitation was able to delay
exposure to polio until adolescence or adulthood, at
(10) which time polio infection produced paralysis. Previ-
ously, 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
(15) example is Lyme disease, which is caused by bacteria
that are transmitted by deer ticks. It occurred only spo-
radically during the late nineteenth century but has
recently become prevalent in parts of the
largely due to an increase in the deer population that
(20) occurred simultaneously with the growth of the suburbs
and increased outdoor recreational activities in the
deer’s habitat. Similarly, an outbreak of dengue hemor-
rhagic fever became an epidemic in
because of ecological changes that caused Aedes aegypti,
(25) the mosquito that transmits the dengue virus, to proliferate
The stage is now set in the
dengue epidemic because of the inadvertent introduction
and wide dissemination of another mosquito, Aedes
albopictus.
124. Which of the following, if true, would most strengthen the author’s assertion about the cause of the Lyme disease outbreak in the (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. 请 问 B如 果 不 起 加 强 的 作 用 ， 那 是 不 是 起 削 弱 的 作 用 呢 ？ 多 谢
这道题我也做错了，我的理解是，是不是说 "Interest in outdoor recreation began to grow" 不一定等同于 "the growth of the suburbs and increased outdoor recreational activities in the deer’s habitat."
因为interest grow 不一定造成人数的实际增加；此外，即使户外活动人数增加，也不一定代表 deer's habitat 的户外活动人数增加。
所以相比之下A更好些。
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