托福阅读修辞目的题是阅读考试中比较常见的一种题型，tpo则是托福阅读备考最权威的材料，所以托福小编综合二者，为大家集中整理了tpo阅读中考察的修辞目的题及其对应的解析，供大家参考使用。本文带来的是TPO31-1的修辞目的题，一起来看看吧。
TPO31-1Speciation in Geographically Isolated Populations
Pragraph 2：Allopatric speciation may be the main speciation route. This should not be surprising, since allopatry is pretty common. In general, the subpopulations of most species are separated from each other by some measurable distance. So even under normal situations the gene flow among the subpopulations is more of an intermittent trickle than a steady stream. In addition, barriers can rapidly arise and shut off the trickle. For example, in the 1800s a monstrous earthquake changed the course of the Mississippi River, a large river flowing in the central part of the United States of America. The change separated populations of insects now living along opposite shore, completely cutting off gene flow between them.
3. Why does the author provide the information that "the subpopulations of most species are separated from each other by some measurable distance"?
A. To indicate how scientists are able to determine whether subpopulations of a species are allopatric.
B. To define what it means for a group of animals or plants to be a subpopulation.
C. To suggest that allopatric speciation is not the only route to subpopulation.
D.To help explain why allopatric speciation is a common way for new species to come about.
3.D 修辞目的题
解题：高亮句前面的一句话，也就是本段的第一句(主旨句)，allopatry是main speciation route。本段都是围绕着这个主题来进行的。所以选择D。
5. In paragraph 2,why does the author mention that some insect populations were separated from each other by a change in the course of Mississippi River caused by an earthquake?
A. To make the point that some kind of physical barrier separates the subpopulations of most species.
B. To support the claim that the condition of allopatry can sometimes arise in a short time.
C. To provide an example of a situation in which gene flow among the subpopulations of a species happens at a slow rate.
D. To explain why insects living along opposite shores of the Mississippi River are very different from each other.
5.B 修辞目的题
解析：For example后面就是题目中的内容，那么也就是说作者用此作为例子来支持前 面的观点。而前面的观点是 barriers也有可能突然发生，然后截断了这种trickle。所以对应的是B。
段落翻译：
【3】地理隔离也能缓慢地进行，会跨越很长的时间段。我们在化石记录中找到了这种长期证据，从中我们可以瞥见先前延续环境的破碎。比如说，在过去的冰河世纪，经过北美和欧洲的冰川最终把种群的部分彼此切断，当冰川消退后，这些分离的动植物种群又会连到一起。一些起源于同一母群的群体变得不再那么容易兼容——它们演化成了分开的物种。然而，在另一些群体里，遗传差异并没有那么明显，后代们还是可以种族内互相交配的繁殖，隔离并没有彻底，所以物种形成就没有发生。
以上就是托福阅读TPO31-1中的修辞目的题及其解析，大家可以在备考的时候参考复习，希望能够帮助大家的考前准备。最后前程百利祝大家都能取得理想的托福考试成绩。
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