Directions: In the following text, some sentences have been removed. For Questions 41-45, choose the most suitable one from the list A-G to fit into each of the numbered blank. There are two extra choices, which do not fit in any of the gaps. Mark your answers on ANSWER SHEET 1.(10 points)
Long before Man lived on the Earth, there were fishes, reptiles, birds, insects, and some mammals. Although some of these animals were ancestors of kinds living today, others are now extinct, that is, they have no descendants alive now. 41. Very occasionally the rocks show impression of skin, so that, apart from color, we can build up a reasonably accurate picture of an animal that died millions of years ago. The kind of rock in which the remains are found tells us much about the nature of the original land, often of the plants that grew on it, and even of its climate.
42. . Nearly all of the fossils that we know were preserved in rocks formed by water action, and most of these are of animals that lived in or near water. Thus it follows that there must be many kinds of mammals, birds, and insects, of which we know nothing.
43. . There were also crab-like creatures, whose bodies were covered with a horny substance. The body segments each had two pairs of legs, one pair for walking on the sandy bottom, the other for swimming. The head was a kind of shield with a pair of compound eyes, often with thousands of lenses. They were usually an inch or two long but some were 2 feet.
44. . Of these, the ammonites are very interesting and important. They have a shell composed of many chambers, each representing a temporary home of the animal. As the young grew larger it grew a new chamber and sealed off the previous one. Thousands of these can be seen in the rocks on the Dorset Coast.
45. .About 75 million years ago the Age of Reptiles was over and most of the groups died out. The mammals quickly developed, and we can trace the evolution of many familiar animals such as the elephant and horse. Many of the later mammals, though now extinct, were known to primitive man and were featured by him in cave paintings and on bone carvings.
［A］ The shell gush have a long history in the rock and many different kinds are known.
［B］ Nevertheless, we know a great deal about many of them because their bones and shells have been preserved in the rocks as fossils. From them we can tell their size and shape, how they walked, the kind of food they ate.
［C］ The first animals with true backbones were the fishes, first known in the rocks of 375 million years ago. About 300 million years ago the amphibians, the animals able to live both on land and in water, appeared. They were giant, sometimes 8 feet long, and many of them lived in the swampy pools in which our coal seam, or layer, or formed. The amphibians gave rise to the reptiles and for nearly 150 million years these were the principal forms of life on land, in the sea, and in the air.
［D］ The best index fossils tend to be marine creatures. These animals evolved rapidly and spread over large areas of the world.
［E］ The earliest animals whose remains have been found were all very simple kinds and lived in the sea. Later forms are more complex, and among these are the sealilies, relations of the starfishes, which had long arms and were attached by a long stalk to the sea bed, or to rocks.
［F］ When an animal dies the body, its bones, or shell, may often be carried away by streams into lakes or the sea and there get covered up by mud. If the animal lived in the sea its body would probably sink and be covered with mud. More and more mud would fall upon it until the bones or shell become embedded and preserved.
［G］ Many factors can influence how fossils are preserved in rocks. Remains of an organism may be replaced by minerals, dissolved by an acidic solution to leave only their impression, or simply reduced to a more stable form.
41.【解析】选［B］。本题主要通过句组关系的理解来解答。跳过空格阅读第一段可以看出，本段主要讲述了史前动物的存在(第一句)、部分种类的灭绝(空格前第二句，句中they have no descendants alive now是对extinct一词的解释)以及从化石(rocks as fossils)中我们所能发现的数百万年前就死掉了的动物的精确印记(空格后第一句)和当时的地貌及气候特征(空格后第二句)。由此，我们就看到了空格前后两个句组所叙述内容之间的矛盾和内容上的不足：1)既然已经"灭绝"，怎么还能了解有关的这一切呢？说明空格前的句子与其空格所在的句子之间具有转折关系。2)空格后第一句中the rocks指的又是什么石头呢？需要在前有所提及，即正确选项中应包含有rock这个词。能够同时满足这两个条件的只有选项［B］。 ［A］、［E］、［G］中也提到了rock，但在句际关系上与前后句组不相吻合，故不正确。所以正确答案只能是［B］。
42.【解析】选［F］。文章第一段说明了化石是我们研究史前动物的主要依据，而本段则主要说明了这些化石的形成。空格后"几乎我们所知的所有化石都是在由于水作用而形成的岩石中保存下来的 (Nearly all of the fossils that we know were preserved in rocks formed by water action) "一句是一个结论性表述，之前应有"水作用形成的岩石(rocks formed by water action)"这一过程的细节描述。［F］的内容正好说明死去动物的尸体是如何被水和泥沙保存下来的，与此恰相吻合，所以选［F］。此题极易错选［G］，因为［G］一开始就有how fossils are preserved，后面又出现了impression一词，在用词上出现明显的复现现象。 但是［G］后面讲的是动物遗体上的有机组织"organism"可能转化成的几种形式，这与下文的内容不相吻合，故不选［G］。
43.【解析】选［E］。本题选择的线索有两条：1)空格后有"There were also crablike creatures……"，说明空白处应有关于另一类动物的内容；2) 从本段开始，文章转向讨论由低级向高级进化中的动物。［E］开始的部分是"The earliest animals whose remains have been found……"，符合文章写作的顺序。［B］与上文相符，但与下文不符，且与全文结构不相吻合。
44.【解析】选［A］。从上一段和本段的 "段际关系"来看，两段属于顺接关系，即两段在相继描述两种不同层级、不同种类的史前动物。从段落结构上来看，两段的开头句都是其主题句，下文接着展开进行细节描述。特别是本段空格后的Of these, ……，标志着空格后一句是空格所在句的拓展句。既然下文一开始就有Of these, ……，空白部分就应该有"some，several，many"或类似的词；再者，此段中关于the ammonites(总类中的一种，考生不必知道其确切含义)的描述，主要阐述了其shell的构造，由此说明shell是其主要特征，故在 "总类"的描述(即空缺句)中应该含有shell一词，这就不难判断答案只能是［A］了。
45.【解析】选［C］。此空独立成段，所以只能从段际关系来分析。因为前两段描述了史前动物由低级向高级的进化过程，而此段后就是结尾段，因此此段必然要起"承上启下"的作用。所谓 "承上"，是指要对上文进行一定的概括、总结；所谓 "启下"则是要引出下文。下文中的"reptile"在本题空白处前面的文章中从没有提到，在下文中又没有作为新信息，因而作为正确答案的选项中一定有这个词。［C］从375 million years ago的化石的发现到300 million years ago的化石的发现，以及此后nearly 150 million years内the reptiles的存在，不但对史前动物的进化过程做了很好的概括，而且为下文the Age of Reptile的出现打下了伏笔，是一个很好的"承上启下"的过渡段，所以正确答案只能是［C］。