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 blanks. There are two extra choices, which do not fit in any of the blanks. 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 fish 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 were 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 sea-lilies, relations of the star-fishes, 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.

　　考纲链接

　　本文严格按照考试大纲的精神选材、设题，文章主干部分总字数为342字，而选项部分总字数为327词，即所有的给出信息总阅读量高达669词。相当于传统阅读题型的一篇半或将近两篇文章的阅读量，因此，该题型要求我们要有较好的阅读方法和一定的阅读理解能力。

　　文章导读

　　本文的文章结构脉络非常清晰，其主题是化石和早期生物的进化。文章首先介绍了什么是史前动物，接下来谈论了化石是什么以及化石形成的过程。文章又谈论了化石中保存的生物种类，以及这些生物是如何进化的：首先是简单的生命形式，如贝类动物，然后是脊椎动物，如两栖动物与哺乳动物。爬行动物的时代结束后，包括人类在内的哺乳动物占据了统治地位。

　　答案与解析

　　41.【答案】B

　　【解析】 文章的第一段中出现的空白处，最有可能的就是让补充主旨句。在做出选择之前，我们必须通读全文至少一遍，并动用自己的归纳总结的能力，尽可能选出最能够涵盖全文内容的选项。在读文章的过程中，我们要学会抓关键词，比如，第二段中有：rock, skin, accurate picture, climate...主要讲动植物在岩石上留下的印记能够让人了解它们的模样甚至所处的气候。第四、五、六段虽不完整，但是我们也能抓一些关键词：fossil, kinds, horny substance, two pairs of legs, shield with a pair of compound eyes, an inch or two long, shell...大致是说通过化石，我们可以知道一些动植物的具体模样，比如第五段就对某一生物进行了具体描述，有几条腿、几只眼等等。由此可见，最能够体现全文内容的只有B。

　　42.【答案】F

　　【解析】 本题是第二段的段首部分，应该是既能与第一段的内容有一定的连贯性，又能与第二段中的重点提示信息相关联的选项。第二段中要点提示线索指出，几乎我们所知道的所有化石都是由于水的作用而被保存在了石头中，而且大多都是生活在水里或水边的动物。选项F末尾的衔接成分“more and more”(越来越多的)与空白之后的“nearly all”(几乎所有的)相互呼应。所以F是正确选项。

　　43.【答案】E

　　【解析】 要选出本题的正确答案必须明确讨论的重心已经转移到了对螃蟹般的复杂动物的描述上。这些生物之前又是什么呢？只有选项E回答了这个问题。人们发现的最早的动物遗骸都是些非常简单的物种，而且都生活在海洋里。后来的物种比较复杂，其中包括海百合，它们是海星的亲戚，海星有长长的触手，可以通过其长柄吸附在海底或石头上。本题的正确选项是E。

　　44.【答案】A

　　【解析】 本题是第四段的段首部分，应该是此段的主题句，在此句中，单词shell起到了举足轻重的承上启下的作用。A谈到了贝类动物及其种类。空白之后的第一个段落里的“Of these”(其中)连接起了贝类与菊石(ammonites)。因此，本题的正确答案应是A。

　　45.【答案】C

　　【解析】 本题是选择一个段落，我们必须从全文的整体结构着手。根据上下文内容提示以及文章第一句，我们知道，此段内容应该既能够承接有壳的水生动物，又能够引出下文爬行动物时代结束这样的内容，因此，所选答案应该是介绍这两种动物之间的生物过渡群种。只有C，它既说到了“鱼类是最先有脊柱的动物”又说到“之后出现的两栖动物”这正好起到了在“低等动物”和“高等动物”之间的联系作用，因此答案是C。

　　全文精译

　　人类生活在地球上的很久以前，地球上有鱼、爬虫、鸟、昆虫和一些哺乳动物。尽管这些动物里有些是现代生物的祖先，但其它的却已灭绝了，也就是说，它们现在已经没有后代了。41)然而，我们对它们了解很多是因为它们的骨骼和外壳作为化石保存在了岩石里，从这些岩石中我们可以看出它们的尺寸和形状，以及它们是如何行走的，以及他们所吃的食物的种类。有时，我们通过岩石的表皮及其颜色精确地描述出死于几百万年前的动物的形象。这些包裹动物尸体的岩石能告知我们这片土地、生长在这片土地上的植物及其气候等特征。

　　42)当一个动物死亡，它的尸体、骨骼和外壳常常被溪流带进湖泊海洋，之后由泥土覆盖。如果是生活在海里的动物，那么它的尸体可能会下沉，被泥石覆盖，越来越多的泥土跌落覆盖在上面，直到骨骼或者外壳完全被包围保存起来。几乎所有我们知道的化石都是保存在由水作用形成的岩石里。这些化石里的动物大多数生活在水里或者靠近水的地区。因此，必然有许多我们还一无所知的动物、鸟类和昆虫生活在它左右。

　　43)已发现的遗留物中最早期的都是生活在海洋中的相当简单的物种。后来的形状更复杂，当中有海合，有着长手臂、由一根通向海底或岩石的长茎吸附的星鱼亲系。也有蟹类生物，它们的身体由角状物覆盖。身体部分每边有两对脚。一对是用来在沙底行走，另一对用来游泳。头是一种防护物，上面有一双复合眼，通常有成千上万个透镜。

　　44)甲壳类动物在岩石里有很长的历史，许多不同的种类已为人类所知。这当中，菊石是很有趣和重要的种类。它们有一个由许多小室组成的壳，每一个代表它临时的家。当一个年幼的菊石长大，它就自己生成一个新室而封存原先那个。在多西特海滩的岩石里可见到成千上万个这样的东西。

　　45)最初真正的脊椎动物是鱼，最早被发现的生活于三亿七千五百万年前。大约在三百亿万年前，两栖动物既能生活在陆地又能生活在水里的动物出现了。它们很大，有时有八英尺长。许多生活在沼泽地里，那里也是煤炭断层形成的地方。两栖动物滋生了爬虫动物。在近一亿五千万年里这些是生活在陆地海洋和空气里的生物的最初形式。

　　在约七百五十万年前，爬虫纪过去，许多种类灭绝。哺乳动物迅速发展，我们可以追溯出许多熟悉动物的进化轨迹如大象和马。许多后来的哺乳动物尽管现在已经灭绝，但却为原始人所知，这在他们的壁画和骨骼雕刻中可以发现。

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