题目

A.dated B.unlikely C.set D.fossils E.estimate F.delicateG.takes H.finds I.exactly J.advocated K.tracked Haul of Fossil Fish Pushes Back the Origin of Teeth and Jaws Our teeth and jaws are incredibly ancient.They're older than dinosaurs，older than arms and legs，older than trees adaptations that paleontologists （古生物学家） have （1） to our distant，fishy relatives that thrived in the seas around 425 million years ago.But a collection of carefully-preserved vertebrates （脊椎动物） found in China has （2） a new date for the earliest record of jaws and teeth.The early vertebrates include some of the earliest fish，one of the earliest relatives of sharks，and，at about 436 million years old，the most ancient （3） yet found of fish with teeth and jaws. Researchers have disagreed about （4） when the earliest bites evolved.Molecular （分子的） studies based upon estimations of genetic changes have （5） that the first jaws and teeth evolved about 450 million years ago.Until now，the oldest fossil of jawed vertebrates-or gnathostomes （6） to about 425 million years ago，a significant gap.As Institute of Vertebrate Paleontology and Paleoanthropology researcher Min Zhu and his colleagues describe in a series of Nature papers published today，the new （7） from South China sit in the middle of this gap and offer a startling look at a critical moment in evolutionary history. Zhu and coauthors note in their research，the fish they uncovered were small and had （8） bones.That means these fish were generally （9） to become fossils except in truly outstanding circumstances where they could be buried quickly and shielded from scavengers （食腐动物） that would otherwise eat them.That an exceptional stroke of luck was required to preserve such fish likely explains the difference between the molecular （10） and fossil record.

A.dated B.unlikely C.set D.fossils E.estimate F.delicate
G.takes H.finds I.exactly J.advocated K.tracked

Haul of Fossil Fish Pushes Back the Origin of Teeth and Jaws    Our teeth and jaws are incredibly ancient.They're older than dinosaurs，older than arms and legs，older than trees adaptations that paleontologists （古生物学家） have （1） ____ to our distant，fishy relatives that thrived in the seas around 425 million years ago.But a collection of carefully-preserved vertebrates （脊椎动物） found in China has （2） ____   a new date for the earliest record of jaws and teeth.The early vertebrates include some of the earliest fish，one of the earliest relatives of sharks，and，at about 436 million years old，the most ancient （3） ____ yet found of fish with teeth and jaws.
    Researchers have disagreed about （4） ____ when the earliest bites evolved.Molecular （分子的） studies based upon estimations of genetic changes have （5） ____ that the first jaws and teeth evolved about 450 million years ago.Until now，the oldest fossil of jawed vertebrates-or gnathostomes （6） ____ to about 425 million years ago，a significant gap.As Institute of Vertebrate Paleontology and Paleoanthropology researcher Min Zhu and his colleagues describe in a series of Nature papers published today，the new （7） ____ from South China sit in the middle of this gap and offer a startling look at a critical moment in evolutionary history.
    Zhu and coauthors note in their research，the fish they uncovered were small and had （8） ____ bones.That means these fish were generally （9） ____ to become fossils except in truly outstanding circumstances where they could be buried quickly and shielded from scavengers （食腐动物） that would otherwise eat them.That an exceptional stroke of luck was required to preserve such fish likely explains the difference between the molecular （10） ____ and fossil record.

题目解答

答案

（1）考查动词。句意：它们比恐龙更古老，比手臂和腿更古老，比树木的进化更古老，古生物学家追溯到大约4.25亿年前在海洋中繁盛的我们的远古鱼类亲属，它们适应了这些特征。根据句意，空处表示"追踪到"，track to为固定短语，表示"追踪到"，结合空前have可知为现在完成时，应填过去分词tracked，故选K项。
（2）考查动词。句意：但是在中国发现的一组精心保存的脊椎动物化石为颚骨和牙齿的最早记录设定了一个新的日期。根据句意，空处表示"设定"，set a new date意为"设定了一个新的日期"，应填set，结合空前has可知为现在完成时，应填过去分词set，故选C项。
（3）考查名词。句意：这些早期的脊椎动物包括一些最早的鱼类，最早的鲨鱼近亲，以及约4.36亿年前发现的这组最古老的有牙齿和颚骨的鱼类化石。根据空前the most ancient可知空处应为名词，结合句意，此处表示"化石"，结合空后"found of fish with teeth and jaws"可知应为名词复数表示泛指，应填fossils，故选D项。
（4）考查副词。句意：研究人员对最早咬合的确切时间存在分歧。根据句意可知空处表示"确切地"，应用副词exactly作状语，修饰后面的句子，故选I项。
（5）考查动词。句意：基于基因变化估计的分子研究认为，最早的颌骨和牙齿是在大约4.5亿年前进化而来的。根据句意可知空处表示"主张，认为"，应为advocate，结合空前have可知为现在完成时，应填过去分词advocated，故选J项。
（6）考查动词。句意：到目前为止，最古老的有颌脊椎动物化石---或者说颌口动物---可以追溯到大约4.25亿年前，这是一个很大的差距。根据句意，空处表示"追溯到"，date to后加时间表示"可追溯到……年"，一般过去时，故选A项。
（7）考查名词。句意：正如古脊椎动物研究所和古人类学研究员朱敏和他的同事在今天发表的一系列《自然》论文中所描述的那样，来自华南的新发现位于这一空白的中间，为进化史上的关键时刻提供了惊人的视角。根据空前the new可知空处应为名词，新发现不止一个，为名词复数形式，应填finds，故选H项。
（8）考查形容词。句意：朱教授和合著者在他们的研究中指出，他们发现的鱼很小，骨头很小。根据空后bones可知，空处为形容词作定语，结合句意，空处表示"细微的"，应为delicate，故选F项。
（9）考查形容词。句意：这意味着这些鱼一般不太可能成为化石，除非在非常特殊的情况下，它们可以迅速被埋起来，不被食腐动物吃掉。be unlikely to do sth.为固定短语，表示"不太可能做某事"，空处应填unlikely，故选B项。
（10）考查名词。句意：要保持这样的鱼类需要一次特殊的幸运机遇，这很可能解释了分子估计和化石记录之间的差异。根据上文"Molecular （分子的） studies based upon estimations of genetic changes（基于遗传变化估计的分子研究）"可知，空处应为名词estimate （估计），表示"分子估计"，故选E项。