托福阅读笔记。说到托福阅读备考，TPO是必不可少的备考神器，通过TPO练习来更好的适应阅读考试的节奏。本文小编带来的是TPO5 The Cambrian Explosion的学习笔记，希望能够与正在备考的大家一起进步。
TPO5 The Cambrian Explosion
文章题材：生命科学—寒武纪大爆发
文章结构：本文介绍寒武纪大爆发，现代动物族群在短暂的寒武纪出现和快速分化，连续性的化石记录缺失的原因，已发现的含有软体动物化石的化石层及他们提供的信息，同时由这些化石层所带来的启示。
第一段：介绍了寒武纪大爆发的含义。
第二段：科学家对寒武纪大爆发的未解之谜。
第三段：对化石记录确实的解释，有可能是因为早期动物大多是软体动物，很难形成化石。
第四-六段：介绍了几种比较广为人知的软体动物化石层，伊迪卡拉化石层、托莫特化石层和伯吉斯页岩化石层。
第七段：动物迅速进化的可能原因，确切的原因无人得知。
常见词汇：
Explosion n. 爆炸;爆发
Timescale时标
Diversification n. 多样化;变化
Discourage vt.使气馁，阻碍
Exclusively adv.排他地(独占地，专门地)
Sediment n. 沉积;沉淀物
Assign vt. 分配;指派
Slide n. 滑动;幻灯片vt. 滑动
Await vt. 等候，等待
Arthropod n.节肢动物
题目设置：
本文中题型的分配是4道词汇题，3道事实信息题，句子插入题、句子简化题、文中总结题等，延续一贯的题目设置。文章结构清晰，难度适中，题目难度适中，在解题时注意找准题干和文章内容的对应。
易错题解析：
Paragraph5: A slightly younger fossil formation containing animal remains is the Tommotian formation, named after a locale in Russia. It dates to the very early Cambrian period, and it also contains only soft-bodied forms. At one time, the animals present in these fossil beds were assigned to various modern animal groups, but most paleontologists now agree that all Tommotian fossils represent unique body forms that arose in the early Cambrian period and disappeared before the end of the period, leaving no descendants in modern animal groups.
7.Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.
A. The animals found in the Tommotian fossil bed were once thought to belong to a variety of modern animal groups, but now they are thought to have descended from a single group.
B. Animals in the Tommotian fossil beds were initially assigned to modern animal groups but are now thought to belong to groups that emerged and died out during the Cambrian period.
C. Though at first they thought otherwise, paleontologists now agree that the animals in the Tommotian have body forms from which modern animals have descended.
D. It is unclear whether the Tommotian fossils from the early Cambrian period represent unique body forms or whether they should be assigned to various modern animal groups.
题型：句子简化题。答案是(B)
解析：原句最核心的关系是转折关系，but后的半句是主要内容。A选项主要信息错，C选项不符合原意，D选项逻辑有误，B选项主要信息和逻辑都符合原意，正确。
Paragraph 5：█ Modern architectural forms generally have three separate components comparable to elements of the human body; a supporting skeleton or frame, an outer skin enclosing the interior spaces, equipment, similar to the body’s vital organs and systems. █ The equipment includes plumbing, electrical wiring, hot water, and air-conditioning. █Of course in early architecture—such as igloos and adobe structures—there was no such equipment, and the skeleton and skin were often one. █
14.Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some answer choices do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.
The term “Cambrian explosion” refers to the geologically brief period during which all modern animal groups evolved.
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Answer Choices
A. Little is known about the stages of evolution during the Cambrian period, in part because early animals were soft bodied and could fossilize only under particular conditions.
B. While animal fossils from before the Cambrian explosion have no modern descendants, many animals that evolved during the Cambrian explosion can be assigned to modern groups.
C. The Cambrian period is significant because it marks the emergence of eukaryotic life-forms – organisms that have cells with true nuclei
D.The Ediacara fossil formation provides the most information about the Cambrian explosion, while the earlier, Tommotian and Burgess Shale formations give clues about Precambrian evolution.
E.Zoologists are awaiting the discovery of a 600-million-year-old fossil formation in order to be able to form a theory of how animal evolution progressed.
F.Although the reasons for the rapid evolution of animals during the Cambrian period are not known, one proposed explanation is an abundance of niches with a lack of competitors.
题型：文章总结题，答案ABF.
解析：本题考查文章大意。C选项是文章细节，而且有误。D选项与文章内容相反，E选项同样是文章细节。所以选项ABF对正确，A选项是第三段的观点，B选项是五六段的观点，F选项是最后一段。
以上就是小编带来的托福阅读笔记之TPO5 The Cambrian Explosion，希望能够和备考的大家一起学习。更多托福考试资讯请关注前程百利。
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