托福阅读选非题讲解

 前言

今天张老师告诉大家这类题目如何完美破解！让我们直入主题：

问题： According to paragraph 3, all of the following characterize the way natural selection stabilized the Australian rabbit population EXCEPT:

A. The most toxic viruses died with their hosts.

B. The surviving rabbits were increasingly immune to the virus.

C. The decline of the mosquito population caused the spread of the virus to decline.

D. Rabbits with specific genetic make-ups were favored.

Paragraph 3: At times, it is actually possible to watch the effects of natural selection in host-parasite relationships. For example, Australia during the 1940 s was overrun by hundreds of millions of European rabbits. The rabbits destroyed huge expanses of Australia and threatened the sheep and cattle industries. In 1950, myxoma virus, a parasite that affects rabbits, was deliberately introduced into Australia to control the rabbit population. Spread rapidly by mosquitoes, the virus devastated the rabbit population. The virus was less deadly to the offspring of surviving rabbits, however, and it caused less and less harm over the years. Apparently, genotypes (the genetic make-up of an organism) in the rabbit population were  that were better able to resist the parasite. Meanwhile, the deadliest strains of the virus perished with their hosts as natural selection favored strains that could infect hosts but not kill them. Thus, natural selection stabilized this host-parasite relationship.

首先，审题。按照关键词定位”way”(只在题目中出现一次),” natural selection”,” rabbit population”去定位，你会发现无论你选择哪个关键词都定位不到一个活几个具体的句子。所以，这道题目要通读段落！

这时候，很多同学的内心已然开始有崩溃迹象。没关系，张老师提供给大家具体的步骤，大家按照步骤做就可以妥妥的攻破这类题。

Step 1: 通读四个选项，并记住关键词。（注意：不强迫自己把所有的内容都记住，大家要相信自己的潜意识中对每个选项是印象的）

A. The most toxic viruses died with their hosts.

B. The surviving rabbits were increasingly immune to the virus.

C. The decline of the mosquito population caused the spread of the virus to decline.

D. Rabbits with specific genetic make-ups were favored.

Step 2: 分意群读段落。

意群1: At times, it is actually possible to watch the effects of natural selection in host-parasite relationships. For example, Australia during the 1940 s was overrun by hundreds of millions of European rabbits. The rabbits destroyed huge expanses of Australia and threatened the sheep and cattle industries. (事件描述). In 1950, myxoma virus, a parasite that affects rabbits, was deliberately introduced into Australia to control the rabbit population.(解决方案)

这时候我们阅读了一件事情和对应的解决方案，回头看选项，通过关键词看出没有对应的选项。继续读文章：

意群2: Spread rapidly by mosquitoes, the virus devastated the rabbit population.

虽然关键词mosquitoes和D选项对应，但是我们发现意思不一致，所以继续读。

意群3: The virus was less deadly to the offspring of surviving rabbits, however, and it caused less and less harm over the years. Apparently, genotypes (the genetic make-up of an organism) in the rabbit population were selected that were better able to resist the parasite.

这个意群主要讲目标群体基因进化了，就像我们现在有各种灭蚊剂，同时蚊子的抗药性也随之增强。看选项：

A. The most toxic viruses died with their hosts.

B. The surviving rabbits were increasingly immune to the virus.

C. The decline of the mosquito population caused the spread of the virus to decline.

D. Rabbits with specific genetic make-ups were favored.

以下找到了B和D两个选项，开心～ 继续读最后一个意群：

意群4: Meanwhile, the deadliest strains of the virus perished (灭亡) with their hosts as natural selection favored strains that could infect hosts but not kill them. Thus, natural selection stabilized this host-parasite relationship.

主要讲细菌的灭亡，我们对应剩下的两个选项：

A. The most toxic viruses died with their hosts.

C.The decline of the mosquito population caused the spread of the virus to decline.

A的描述是对的。所以我们就得出四个选项中只有C是不对的，身为选非题，我们答案就出来啦。

所以，我们的做题步骤是：看选项确定关键词－读意群1－对应选项－读意群2-对应选项。。。

百试百灵哦，小伙伴们赶紧去试试吧！