In the following article, 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 gaps. Mark your answers on ANSWER SHEET 1. (10 points) DiX顺利考研网
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) . DiX顺利考研网
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. DiX顺利考研网
(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. DiX顺利考研网
(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. DiX顺利考研网
(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. DiX顺利考研网
(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. DiX顺利考研网
［ A］The shellfish have a long history in the rock and many different kinds are known. DiX顺利考研网
［ 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. DiX顺利考研网
［ C］The first animals with true backbones were 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, 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. DiX顺利考研网
［ D］The best index fossils tend to be marine creatures. These animals evolved rapidly and spread over large areas of the world. DiX顺利考研网
［ 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. DiX顺利考研网
［ 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 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. DiX顺利考研网
［ 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. DiX顺利考研网
第一段指出：在人类出现很早以前，地球上就出现了鱼类、爬行动物、鸟类和一些哺乳动物（这是对全文的一个概述，点出本文的话题）。虽然这些动物有一些是现今生活着的各种动物的祖先，但是另一些动物现在已经灭绝了，即它们现在已经没有活着的后代了。第二句是个表示让步关系的句子，重点是主句部分： others are now extinct, that is, they have no descendants alive now，而that is表明they have no descendants alive now是同位语结构，因此本段要点词语为others are now extinct。这为回答第41题从意思和逻辑上都提供了主要依据。 DiX顺利考研网
第二段首句指出：偶然根据石头里所显示出来的印记，我们可以合理地推断出几百万年前灭绝了的某种动物的准确外形，尽管不能确定其颜色。此句前后是因果关系，提到了 rocks，结果是so that…we can build up…picture。后面又接着讲rocks in which the remains are found。由此可知，这些是本段的要点词语。 DiX顺利考研网
第三段中已知信息是：我们所知道的所有化石几乎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。因此，肯定存在过许多我们一无所知的哺乳动物、鸟类和昆虫类。空白后第一句是个并列句，主语分别是 Nearly all of the fossils和 most of these (the fossils)，而且都与water action有关。这为回答第42题提供了主要线索。 DiX顺利考研网
第五段空白后第一句中有指代词 of these，these必定指代前文提到的复数名词。紧接着提到的ammonites是“这些贝壳类动物”的一种。后面有对它的描述：ammonites非常有趣而又很重要。它们身体上有个由许多腔室构成的硬壳（shell），每个腔室都代表着这个动物的临时住所。这样，上一句提到的自然应该与贝壳类动物有关，为回答第44题提供了线索。 DiX顺利考研网
第 42题表达的内容，应该是既能与第二段的内容有一定的连贯性，又能与第三段中的重点信息相关联。尤其明显的是，选项［F］的最后一句与空白后的第一句紧密衔接。空白后第一句讲：我们所知道的几乎所有化石都是被保存在了由于水的作用而形成的岩石中，而且大多都是生活在水里或水边的动物。选项［F］中涉及到相关的词：be carried away by streams into lakes or the sea， get covered by mud等，都是在讲水的作用形成化石；而最后一句“直到其骨头或外壳嵌进石头并被保存下来”，preserved一词在空白后第一句中重复出现，使前后两句之间紧密衔接。因此［F］为此处正确答案。［F］意为：当一个动物死去后，其身体、骨头或外壳通常可能会被溪流冲进湖泊或大海，在那里被淤泥覆盖起来。要是这种动物生活在海里，它的身体可能会沉到海底被淤泥盖住。淤泥一层层地堆积，直至其骨头或外壳嵌进石头并被保存下来。 DiX顺利考研网
第 45题的内容也应该能将前后两段内容有机地衔接起来。我们知道，上段主要讲的是有壳水生动物。再仔细阅读下段，第一句讲：大约7 500万年前，爬行动物时代结束了。由此可知，要填入的文字应该既承接上段提到的有壳水生动物，又能够引出下文的爬行动物这样的内容。只有选项［C］中有相关的词gave rise to the reptiles。［C］意为：最早的有脊椎的动物是鱼类，已知的最早的鱼类是在3.75亿年前的化石中。大约3亿年前，既能生活在水里又能生活在陆地上的两栖动物出现了。它们形态巨大，有时可达8英尺之长，大多生活在沼泽地里，而煤层也是在这里形成的。由两栖动物又产生了爬行动物，在将近1.5亿年间，它们是生活在陆地上、海洋里及天空中的主要生命形式。 DiX顺利考研网
