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  3. Long before Man lived on the Earth, there were fishes, reptiles, birds, insects, and some mammals. Although some of these animal

Long before Man lived on the Earth, there were fishes, reptiles, birds, insects, and some mammals. Although some of these animal

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问题     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.【B1】________
    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. That 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.
    【B2】______________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.
    【B3】________________There were also crablike 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.
    【B4】________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.
    【B5】________
    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 shellfish 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, was 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 creature. 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 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.
【B5】
选项
答案C
解析 本题可以组合运用时间、地点、数字等线索衔接关系定位法和复现结构定位法。第5题空出的是一整段，这样第5题就涉及与下一段的衔接，即从7个选项中选出一个最合适的选项信息能够与第5题下面一段中的信息连贯衔接起来。在第5题下面一段中的信息可以发现一个时间信息点about 75 million years ago(大约7,500万年前)，再根据该段文章的已知信息，可知此处大概是在描述地球上生物的更替，这种描写很可能就是依据时间的线索展开的，因此完全可以合理推断处于第5题的段落信息很可能与它之后的段落存在着时间线索上的顺延衔接关系，由此需要在7个选项中重点查找哪个选项中也包含有时间信息点，然后总结这些时间信息点之间的关系。选项C)的信息中可以定位出三个时间信息点：375 million years ago、300 million years ago和150 million years ago，这三个时间信息点与第5题下一段中的75 million years ago形成了明显的前后顺序性的衔接关系，即这些时间点将上下文的信息连贯地衔接起来，因此选项C)是第5题的唯一正确答案。同时，第5题下一段的首句为：About 75 million years ago the Age of Reptiles(爬行动物)was over and most of the groups died out．可以从中定位出reptiles这个信息点，而且此句直接定义出“爬行动物时代结束了”。由于文章此处是在讲述地球上生物的更替，因此可以判断文章此处的信息点reptiles不应该是第一次被提及，因此我们可以去选项中寻找reptiles的复现结构。选项C)中：The amphibians gave rise to the reptiles and for nearly 1 50 million years these were the principal forms of life on land，in the sea，and in the air(两栖动物让位于爬行动物，并且在1亿5,000万年中这些两栖动物是陆地上、海洋中和空中的主要生命形式。)本句出现了这个复现结构，而且该选项有关reptiles的信息恰恰是谈生物的更替，与下一段落可以非常恰当地衔接。
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