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1、 威 学 教 育 |专 注 雅 思 、 托 福 等 出 国 考 试 培 训 网 址 ：【王鑫托福阅读】托福 TPO5-3 阅读文本TPO5TPO5-3 The Cambrian Explosionsignificant” in the passage is closest in1. The word meaning toA. numerousB. importantC. unexplainedD. sudden2. The word “relatively” in the passage is closest in meaning toA. surprisinglyB. collectivel
2、yC. comparativelyD. characteristically3. The word “diversification” in the passage is closest in meaning toA. emergence of many varietiesB. steady decline in number 威 学 教 育 |专 注 雅 思 、 托 福 等 出 国 考 试 培 训 网 址 ：C. gradual increase in body sizeD. sudden disappearance4. The period discussed in the passage
3、 is re an “explosion” because itA. occurred 0.6 billion years ago, late in Earths historyB. was characterized by the unusually fast evolution of many new life-formsC. was characterized by widespread animal extinctionD. was characterized by violent volcanic eruptions5. According to Paragraph 2, which
4、 of the following is NOT a question that paleontologists asked about the Cambrian explosion?A. Why was the origin of life a simple step in Earth s history?B. Why did it take so long for multicellular organisms to develop?C. Why did animal life evolve so rapidly?D. Why does the fossil record lack evi
5、dence of animal evolution during that time?ferred to asThe geologic timescale is marked by significant geologic and biological events, including the origin of Earth about 4.6 billion years ago, the origin of life about 3.5 billion years ago, the origin of eukaryotic life-forms (living things that ha
6、ve cells with true nuclei) about 1.5 billion years ago, and the origin of animals about 0.6 billion years ago. The last event marks the beginning of the Cambrian period. Animals originated relatively late in the history of Earthin only the last 10 percent of Earths history. During a geologically bri
7、ef 100-million-year period, all modern animal groups (along with other animals 威 学 教 育 |专 注 雅 思 、 托 福 等 出 国 考 试 培 训 网 址 ：that are now extinct) evolved. This rapid origin and diversification of animals is often referred to as “the Cambrian explosion.”Scientists have asked important questions about th
8、is explosion for more than a century. Why did it occur so late in the history of Earth? The origin of multicellular forms of life seems a relatively simple step compared to the origin of life itself. Why does the fossil record not document the series of evolutionary changes during the evolution of a
9、nimals? Why did animal life evolve so quickly? Paleontologists continue to search the fossil record for answers to these questions.6.Which of the following best describes the relationship between paragraph 2 and paragraph 3?A. Paragraph 2 puts forward several scientific claims, one of which is rejec
10、ted in paragraph 3.B. Paragraph 2 poses several questions, and paragraph 3 offers a possible answer to one of them.C. Paragraph 2 presents outdated traditional views, while paragraph 3 presents the current scientific conclusions.D. Paragraph 2 introduces a generalization that is illustrated by speci
11、fic examples in paragraph 3.promote” in the passage is closest in7.The word meaning toA. complicateB. preventC. encourageD. affect癌 威 学 教 育 |专 注 雅 思 、 托 福 等 出 国 考 试 培 训 网 址 ：vOne interpretation regarding the absence of fossils during this important 100-million-year period is that early animals were
12、soft bodied and simply did not fossilize. Fossilization of soft-bodied animals is less likely than fossilization of hard-bodied animals, but it does occur. Conditions that promote fossilization of soft-bodied animals include very rapid covering by sediments that create an environment that discourage
13、s decomposition. In fact, fossil beds containing soft-bodied animals have been known for many years.1. Which of the following is NOT mentioned in paragraph 4 as being true of the Ediacara formation?A. It contains fossils that date back to the Precambrian period.B. It contains only soft-bodied animal
14、 fossils.C. It is located on a single site in Australia.D. It does not contain any fossils of the ancestors of modern animals.The Ediacara fossil formation, which contains the oldest known animal fossils, consists exclusively of soft-bodied forms. Although named after a site in Australia, the Ediaca
15、ra formation is worldwide in distribution and dates to Precambrian times. This 700-million-year-old formation gives few clues to the origins of modern animals, however, because paleontologists believe it represents an evolutionary experiment that failed. It contains no ancestors of modern animal gro
16、ups.2. 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.
