It was not until theCambrianperiod, beginning about 600 million years ago, that a greatproliferationof macroscopicspeciesoccurred on Earth and produced afossilrecordthat allows us totrackthe rise and fall ofbiodiversity. Since theCambrianperiod,biodiversityhas generally risen, but there have been somenotableexceptions. Biodiversitycollapseddramaticallyduring atleastfive periods because ofmassextinctions around the globe. The fivemajormassextinctions receive most of theattention, but they are only one end of aspectrumofextinctionevents. Collectively, morespecieswentextinctduring smaller events that were lessdramaticbut more frequent. The best known of the fivemajorextinctionevents, the one that saw thedemiseof the dinosaurs, is the Cretaceous-Tertiaryextinction.

Starting about 280 million years ago, reptiles were thedominantlarge animals interrestrialenvironments. Inpopularlanguage this was theera“when dinosaurs ruled Earth,” when a widevarietyofreptilespeciesoccupying manyecologicalniches. However, no group orspeciescanmaintainits dominanceindefinitely, and when, after over 200 million years, the age of dinosaurs came to adramaticend about 65 million years ago, mammals began toflourish, evolving fromrelativelyfew types of smallterrestrialanimals into themyriadofdiversespecies, including bats and whales, that we know today. Paleontologistslabelthis point in Earth’shistoryas the end of theCretaceousperiod and the beginning of theTertiaryperiod, often abbreviated as the K-Tboundary. This time was alsomarkedby changes in many other types of organisms. Overall, about 38 percent of the families ofmarineanimals were lost, with percentages much higher in some groups Ammonoid mollusks went from being verydiverseandabundantto beingextinct. An extremelyabundantset ofplanktonicmarineanimals called foraminifera largely disappeared, although they rebounded later. Among plants, the K-Tboundarysaw a sharp butbriefrise in theabundanceofprimitivevascularplants such as ferns,clubmosses, horsetails, and conifers and other gymnosperms. The number of flowering plants (angiosperms) was reduced at this time, but they then began to increasedramatically.

What caused these changes? For many years scientists assumed that a cooling of theclimatewasresponsible, with dinosaurs being particularlyvulnerablebecause, like modern reptiles, they wereectothermic(dependent onenvironmentalheat, or cold-blooded). It is now widely believed that atleastsomespeciesof dinosaurs had ametabolicratehigh enough for them to be endotherms (animals thatmaintainarelativelyconsistentbody temperature by generating heat internally). Nevertheless,climaticexplanations for the K-Textinctionare not really challenged by the ideas that dinosaurs may have beenendothermic, becauseevenendotherms can be affected by asignificantchange in theclimate.

Explanations for the K-Textinctionwere revolutionized in 1980 when a group ofphysicalscientists led by Luis Alvarez proposed that 65 million years ago Earth wasstuckby a 10-kilometer-widemeteoritetraveling at 90,000 kilometers per hour. They believed that thisimpactgenerated a thick cloud of dust that enveloped Earth, shutting out much of theincomingsolarradiationand reducing plantphotosynthesisto very low levels. Short-term effects might have included hugetidalwaves andextensivefires. In other words, aseriesof events arising from a single cataclysmic event caused themassiveextinctions. Initially, themeteoritetheorywas based on a singlelineofevidence. At locations around the globe, geologists had found an unusually highconcentrationofiridiumin thelayerofsedimentaryrocks that was formed about 65 million years ago. Iridiumis anelementthat is usually uncommon near Earth’s surface, but it isabundantin some meteorites. Therefore, Alvarez and his colleagues concluded that it was likely that theiridiuminsedimentaryrocks deposited at the K-Tboundaryhad originated in agiantmeteoriteorasteroid. Most scientist came to accept themeteoritetheoryafterevidencecame to light that acircularformation, 180 kilometers indiameterand centered on the northcoastof the Yucatan Peninsula, was created by ameteoriteimpactabout 65 million years ago.

Questions:
question_stem: The word “proliferation” in the passage is closest in meaning to
choices: tag: A
text: decline

tag: B
text: extinction

tag: C
text: increase

tag: D
text: migration
answer_key: C
explanation: 【题目翻译】单词“proliferation”与下列哪一个意思最相近？
A 选项 decline（下降），
B 选项的 extinction（灭绝），
C 选项 increase（增加）
D 选项 migration（迁徙）

【判定题型】：题目要求选出与高亮单词意思最接近的选项，故判断本题为词汇题。

【关键词定位】：根据关键词“proliferation”,定位到原句“It was not until the Cambrian period, beginning about 600 million years ago, that a great proliferation of macroscopic species occurred on Earth and produced a fossil record that allows us to track the rise and fall of biodiversity.”

【词汇解析】：词汇“proliferation”的意思是“ 繁殖, 激增”,带入到原句中，原句的意思是“直到大约6亿年前开始的寒武系时期，地球上才发生了大量的宏观物种扩散，并产生了一种化石记录，使我们能够追踪生物多样性的兴衰。”

【选项分析】
A 选项 decline（下降），不符，错误
B 选项的 extinction（灭绝），不符，错误
C 选项 increase（增加），同义替换，正确
D 选项 migration（迁徙）不符，错误

question_stem: Paragraph 1 supports which of the following statements about life on Earth before the Cambrian period?
choices: tag: A
text: Biodiversity levels were steady, as indicated by the fossil record.

tag: B
text: Levels of biodiversity could not be tracked.

tag: C
text: The most dramatic extinction episode occurred.

tag: D
text: Few microscopic species existed.
answer_key: B
explanation: 【题目翻译】第1段支持以下关于寒武纪之前地球上生命的陈述中的哪一个？
A：化石记录表明，生物多样性水平稳定。
B：无法追踪生物多样性的水平。
C：最引人注目的灭绝事件发生了。
D：很少微生物存活。

【判定题型】：题目问的是文章中的具体细节信息，故根据题目问法可以判断本题为事实信息题。

【关键词定位】用 before the Cambrian period 定位到： It was not until the Cambrian period, beginning about 600 million years ago, that a great proliferation of macroscopic species occurred on Earth and produced a fossil record that allows us to track the rise and fall of biodiversity. 意思是“直到六亿年前的寒武纪，肉眼可看的物种才在地球上兴起。多亏了化石的帮助，我们现在可以了解到物种的兴衰。”

【逻辑分析】可知，直到寒武纪才能够监测生物多样性。言外之意就是在寒武纪之前就不能监测生物多样性。

【选项分析】
A.文章“无法检测生物多样性”，选项与文章相反，故错误。
B.符合文意，正确。
C.恐龙灭绝的是发生在白垩—第三纪的灭绝，这是最引人注目的灭绝，所以选项错误。
D.文章未提及微生物很少存活下来，故错误。

question_stem: 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.
choices: tag: A
text: The dominance of dinosaurs came to an end 65 million years ago, at which time mammals began to flourish and diversify.

tag: B
text: Because no group of species can remain dominant forever, mammals became the dominant group when dinosaurs became extinct.

tag: C
text: After being the dominant group for more than 200 million years, the age of dinosaurs came to a dramatic end 65 million years ago.

tag: D
text: The diverse group of mammals that we know today, including bats and whales, evolved from small terrestrial forms that had been dominated by dinosaurs.
answer_key: A
explanation: 【题目翻译】下面哪句话最能表达文章中突出显示的句子中的基本信息？错误的选择会以重要的方式改变意义，或者遗漏重要的信息。
【判定题型】：根据题目问法，题目要求选择和高亮句意思逻辑都最为接近的句子，故判断本题为句子简化题。
【句子分析】该长句其实是2个长句的并列，将一些不重要的成分去掉如插入语，举例结构等，可以缩略成：However, no group or species can maintain its dominance indefinitely, and mammals began to flourish.主要分成2个意思: 第一是没有任何一种生物能永远地统治, 第二是恐龙灭亡之后, 哺乳动物开始发展统治,且2层意思之间可以构成因果关系。
【选项分析】
A：恐龙的统治地位在6500万年前就结束了，那时哺乳动物开始繁荣和多样化。是原句主要内容的转述，正确。
B：因为没有一个物种可以永远保持优势，所以当恐龙灭绝时，哺乳动物成为优势物种。这两者没有因果关系，不能解释为什么是溥儒动物代替了恐龙，属于逻辑错误。
C：恐龙在2亿多年的统治时期之后，6500万年前，恐龙的时代戏剧性地结束了。未提到哺乳动物，故错误。
D：我们今天所知道的各种各样的哺乳动物，包括蝙蝠和鲸鱼，都是从小型陆地动物进化而来的，它们是由恐龙统治的。文中未提到，属于无中生有，故错误。

question_stem: According to paragraph 2, why are dinosaurs popularly said to have “ruled Earth” during the Cretaceous period?
choices: tag: A
text: Dinosaurs were the only species of reptile that existed during the whole of the Cretaceous period.

tag: B
text: Dinosaurs won the battle for food resources over mammals during the Cretaceous period.

tag: C
text: Dinosaurs survived extinction during the Cretaceous period, whereas many other animal species did not.

tag: D
text: Dinosaurs were the physically and ecologically dominant animals during the Cretaceous period.
answer_key: D
explanation: 【题目翻译】根据第2段，为什么人们普遍认为恐龙在白垩纪“统治地球”？
A：恐龙是整个白垩纪唯一存在的爬行动物。
B：在白垩纪，恐龙战胜了哺乳动物，赢得了食物资源的战争。
C：恐龙在白垩纪灭绝后幸存下来，而其他许多动物物种没有。
D：在白垩纪，恐龙是在身体和生态方面都是统治性的动物。

【判定题型】：题目问的是文章中的具体细节信息，故根据题目问法可以判断本题为事实信息题。

【关键词定位】用 ruled Earth 定位到第二句话，而原因则出现在其前一句话： Starting about 280 million years ago, reptiles were the dominant large animals in terrestrial environments. In popular language this was the era “when dinosaurs ruled Earth,” when a wide variety of reptile species occupying many ecological niches. 意思是“从2.8亿年前开始，爬行动物是陆地环境中主要的大型动物。在流行语中，这是“恐龙统治地球的时代”，当时各种爬行动物占据了许多生态位。”

【逻辑分析】从第一句话可知，280 million 年前，爬行动物是占据主导地位的大型陆地动物。这也就是为什么说是“恐龙支配的时代”。

【选项分析】
A.A 选项的 only 太过绝对了，和原文的 dominant 有出入。故错误。
B.文章未提及，故错误。
C.文章未提及，故错误。
D.符合文章，故正确。

question_stem: According to paragraph 2, which of the following species initially increased in number at the K-T boundary?
choices: tag: A
text: Dinosaurs

tag: B
text: Foraminifera

tag: C
text: Ferns

tag: D
text: Ammonoid mollusks
answer_key: C
explanation: 【题目翻译】根据第2段，以下哪些物种在 K-T 边界处的数量最初有所增加？
A：恐龙
B：有孔虫
C：蕨类植物
D：菊石软体动物

【判定题型】：题目问的是文章中的具体细节信息，故根据题目问法可以判断本题为事实信息题。

【关键词定位】根据关键词“K-T boundary”,定位到 Passage 2倒数第2句，原句为“Among plants, the K-T boundary saw a sharp but brief rise in the abundance of primitive vascular plants such as ferns, club mosses, horsetails, and conifers and other gymnosperms.”，意思是“对植物来说，短时期突然出现了大量的原始维管植物，比如说蕨类植物，石松类植物，木贼类植物，松柏类植物和其他裸子植物。”

【逻辑分析】在定位句中提到了"ferns, club mosses, horsetails, and conifers and other gymnosperms"。

【选项分析】
A.虽然在段中都有提及，但都不是题干所问的内容。
B.虽然在段中都有提及，但都不是题干所问的内容。
C.定位句中提到的和 C 选项呼应。故正确。
D.虽然在段中都有提及，但都不是题干所问的内容。

question_stem: Why does the author note that “even endotherms can be affected by a significant change in the climate”?
choices: tag: A
text: To argue that there was a significant climate at the time that endothermic dinosaurs became extinct

tag: B
text: To argue that climate change caused some dinosaurs to evolve as endotherms

tag: C
text: To support the view that at least some of the dinosaurs that became extinct were endotherms

tag: D
text: To defend climate change as possible explanation for the extinction of dinosaurs
answer_key: D
explanation: 【题目翻译】为什么作者注意到“即使是恒温动物也会受到气候显著变化的影响”？
A：认为恒温恐龙灭绝时有一个重要的气候影响。
B：认为气候变化导致一些恐龙进化为恒温动物。
C：为了支持这样一种观点，即至少一些灭绝的恐龙是恒温动物。
D：以辩护气候变化为恐龙灭绝的可能解释。

【判定题型】：根据题干问法“why ……note”，题目询问“even endotherms can be affected by a significant change in the climate”的修辞目的，可以判断本题为修辞目的题。

【关键词定位】：根据题目,定位到 Passage 3 最后一句，原句为“Nevertheless, climatic explanations for the L-T extinction are not really challenged by the ideas that dinosaurs may have been endothermic。”

【引用内容分析】题干中的 even 甚至, 表示程度的递进。即后半句的原因解释了气候理论为什么不被反驳。

【选项分析】
A.与 D 选项相反，文章“这一论断未真正挑战 K-T 灭绝的气候变化原因”，说明不一定是因为气候。故错误。
B.文章未提及“进化”这一说，故错误。
C.文章未提及，故错误。
D.符合文意，故正确。

question_stem: The word “generated” in the passage is closest in meaning to
choices: tag: A
text: collected

tag: B
text: produced

tag: C
text: spread

tag: D
text: added
answer_key: B
explanation: 【题目翻译】单词“generated”与下列哪一个意思最相近？
A：collected，收集
B：produced，产生
C：spread，传播
D：added，增加

【判定题型】：题目要求选出与高亮单词意思最接近的选项，故判断本题为词汇题。

【关键词定位】：根据关键词“generated”,定位到原句“They believed that this impact generated a thick cloud of dust that enveloped Earth, shutting out much of the incoming solar radiation and reducing plant photosynthesis to very low levels. ”。

【词汇解析】词汇“generated”的意思是“产生; 引起, 对应”,带入到原句中，原句的意思是“他们认为，这一撞击产生了一团厚厚的尘埃，将地球包裹起来，将进入地球的大部分太阳辐射拒之门外，并将植物的光合作用降低到非常低的水平。”

【选项分析】
A：collected，收集，不符，错误
B：produced，产生，同义替换，正确
C：spread，传播，不符，错误
D：added，增加，不符，错误

question_stem: The word “extensive” in the passage is closest in meaning to
choices: tag: A
text: widespread

tag: B
text: sudden

tag: C
text: numerous

tag: D
text: subsequent
answer_key: A
explanation: 【题目翻译】单词“extensive”与下列哪一个意思最相近？
A：widespread，广泛的
B：sudden，突然的
C：numerous，巨大的
D：subsequent，后来的

【判定题型】：题目要求选出与高亮单词意思最接近的选项，故判断本题为词汇题。

【关键词定位】：根据关键词“extensive”,定位到原句“Short-term effects might have included huge tidal waves and extensive fires.”。

【词汇解析】：词汇“extensive”的意思是“广泛的”,带入到原句中，原句的意思是“短期影响可能包括巨大的潮汐波和广泛的火灾。”

【选项分析】
A：widespread，广泛的，同义替换，正确
B：sudden，突然的，不符，错误
C：numerous，巨大的，不符，错误
D：subsequent，后来的，不符，错误

question_stem: According to paragraph 4, all of the following contributed to the massive extinctions of the K-T period EXCEPT:
choices: tag: A
text: tidal waves

tag: B
text: fires

tag: C
text: insufficient solar radiation

tag: D
text: iridium
answer_key: D
explanation: 【题目翻译】根据第4段，除以下情况外，以下所有情况都促成了 K-T 时期的大规模灭绝：
A：潮汐波
B：火灾
C：太阳辐射不足
D：铱

【判定题型】：根据题干中出现的大写“EXCEPT”/"NOT" 等其他明显表示否定的词，可以判定本题为否定事实信息题，需要找出与原文信息不符的那个答案。

【关键词定位】：根据题干关键词“ contributed to”,可以将出题范围锁定在 Passage 4。

【选项分析】
A 选项的 tidal waves，
B 选项的 fires 定位到： Short-term effects might have included huge tidal waves and extensive fires. In other words, a series of events arising from a single cataclysmic event caused the massive extinctions. 对应 A 选项, B 选项。 
C 选项的 solar radiation 定位到： They believed that this impact generated a thick cloud of dust that enveloped Earth, shutting out much of the incoming solar radiation and reducing plant photosynthesis to very low levels. 意思是这种冲击产生了大量的厚尘云, 遮蔽了天空和阳光。对应 C 选项。 
D 选项的 iridium 定位到： At locations around the globe, geologists had found an unusually high concentration of iridium in the layer of sedimentary rocks that was formed about 65 million years ago... 从这里可以知道，iridium 是有关灭绝的证据, 但并非构成灭绝的原因。所以 D 错。

question_stem: According to paragraph 4, which of the following statements explains the importance of the discovery of high levels of iridium rocks?
choices: tag: A
text: It provided evidence that overexposure to solar radiation led to the K-T extinction.

tag: B
text: It showed that more than one cataclysmic event was responsible for the K-T extinction.

tag: C
text: It suggested that the cause of the K-T extinction may have been a meteorite striking Earth.

tag: D
text: It provided evidence that the K-T extinction occurred 65 million years ago.
answer_key: C
explanation: 【题目翻译】根据第4段，以下哪项陈述解释了发现高含量铱岩石的重要性？
A：它提供了过度暴露于太阳辐射导致 K-T 灭绝的证据。
B：这表明导致 K-T 灭绝的原因不止一次。
C：这表明 K-T 灭绝的原因可能是陨石撞击地球。
D：它提供了 K-T 灭绝发生在6500万年前的证据。

【判定题型】：题目问的是文章中的具体细节信息，故根据题目问法可以判断本题为事实信息题。

【关键词定位】用 high levels of iridium rocks 定位到：At locations around the globe, geologists have found an unusually high concentration of iridium in the layer of sedimentary rocks that was formed about 65 million years ago. 意思是“在世界各地的很多地方，地质学家发现铱元素在六千五百万年前的沉积岩层中含量异常丰富。”

【逻辑分析】定位句这句话中并没有说出它的 importance, 可以在这句话附近寻找答案，下文中这句话就是答案出处： Therefore, Alvarez and his colleagues concluded that it was likely that the iridium in sedimentary rocks deposited at the K-T boundary had originated in a giant meteorite or asteroid. Most scientist came to accept the meteorite theory after evidence came to light that a circular formation, 180 kilometers in diameter and centered on the north coast of the Yucatan Peninsula, was created by a meteorite impact about 65 million years ago. 这里说了这么高浓度的 iridium (铱)可能是来自于大的流星或小行星。因此其重要性就是说明该撞击理论是物种大灭绝的原因。

【选项分析】
A.高浓度的 iridium (铱)可能是来自于大的流星或小行星，说明了物种大灭绝可能是因为陨石撞击地球，故选项错误。
B.文中只提及了物种大灭绝可能是因为陨石撞击地球，也未说原因到底有几次。故选项错误。
C.符合文意，故正确。
D.六千五百万年前陨星撞击发生，但是文章未提及是否 K-T 灭绝发生在6500万年前。故选项错误。

question_stem: According to paragraph 4, which of the following is true about the Yucatan Peninsula?
choices: tag: A
text: The circular formation there was caused by a meteorite impact 65 million years ago.

tag: B
text: Sedimentary rocks from that area have the lowest iridium concentration of any rocks on Earth.

tag: C
text: There is evidence that a huge tidal wave occurred there 65 million years ago.

tag: D
text: Evidence found there challenged the meteorite impact theory.
answer_key: A
explanation: 【题目翻译】根据第4段，关于尤卡坦半岛，以下哪一项是正确的？
A：那里的环形构造是6500万年前陨石撞击造成的。
B：那个地区的沉积岩的铱含量是地球上所有岩石中最低的。
C：有证据表明，6500万年前那里发生了一次巨大的海啸。
D：在那里发现的证据挑战了陨石撞击理论。

【判定题型】：题目问的是文章中的具体细节信息，故根据题目问法可以判断本题为事实信息题。

【关键词定位】用 Yucatan Peninsula 定位，定位到: Most scientists came to accept the meteorite theory after evidence came to light that a circular formation, 180 kilometers in diameter and centered on the north coast of the Yucatan Peninsula, was created by a meteorite impact about 65 million years ago. 意思是“大多数科学家在发现直径180公里、以尤卡坦半岛北海岸为中心的圆形构造是由6500万年前的一次陨石撞击形成后，才开始接受陨石理论。”

【逻辑分析】在 Yucatan Peninsula 背岸的大坑是陨石撞击的结果。

【选项分析】
A.符合文意，故正确。
B.说的是“沉积岩的铱含量”和 Yucatan Peninsula 不相关。故错误。
C.说的是“发生了海啸”和 Yucatan Peninsula 不相关。故错误。
D.说的是“证据挑战陨石理论”和 Yucatan Peninsula 不相关。故错误。

question_stem: Which of the following can be inferred from paragraph 4 about the meteorite theory?
choices: tag: A
text: The data originally presented as evidence for the theory were eventually rejected.

tag: B
text: Many scientists did not accept it when it was first proposed.

tag: C
text: It has not been widely accepted as an explanation for the K-T extinction.

tag: D
text: Alvarez subsequently revised it after a circular formation was found in the Yucatan Peninsula.
answer_key: B
explanation: 【题目翻译】以下哪一项可以从关于陨石理论的第4段中推断出来？
A：最初作为理论证据的数据最终被拒绝了。
B：很多科学家在第一次提出时不接受它。
C：它还没有被广泛接受作为对 K-T 灭绝的解释。
D：阿尔瓦雷斯随后在尤卡坦半岛发现了一个圆形构造后对其进行了修改。

【判定题型】：根据题干中出现的关键词“imply”/“infer”/“suggest”等其他表示推断的词，判定本题为推理题。

【关键词定位】没有特别好的关键词，需要整段理解 Passage4。

【逻辑分析】从这句话：Initially, the meteorite theory was based on a single line of evidence. 得知，一开始仅依赖于单一证据的理论, 暗示了证据还不够充分。而后文章说找到了高浓度的 iridium (铱), 理论有了证据的支持，从“Most scientists came to accept the meteorite theory after evidence came to light that a circular formation, 180 kilometers in diameter and centered on the north coast of the Yucatan Peninsula, was created by a meteorite impact about 65 million years ago. ”这句话可以知道，在环形坑证据出现之后大多数的科学家才开始接受小行星撞击理论, 也就是说一开始大多数科学家对该理论是持有怀疑态度的。

【选项分析】
A.没有被拒绝，虽然一开始科学家们是持有怀疑态度的，但是最终逐渐接受了，故选项错误。
B.文中的“科学家的怀疑态度”与选项 B 相对应，故 B 选项正确。
C.文中“科学家们逐渐接受了陨星理论，因为他们看到了六千五百万年前陨星撞击产生的圆形构造的证据。”选项不符合文章原意，故错误。
D.文章未提及“revised”，故错误。