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.

　�。跘］ The shell gush have a long history in the rock and many different kinds are known.

　�。跙］ 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.

　�。跠］ The best index fossils tend to be marine creatures. These animals evolved rapidly and spread over large areas of the world.

　�。跡］ 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�瞝ilies, relations of the star�瞗ishes, which had long arms and were attached by a long stalk to the sea bed, or to rocks.

　�。跢］ 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.

　�。跥］ 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】選［B］。本題主要通過句組關(guān)系的理解來解答。跳過空格閱讀第一段可以看出，本段主要講述了史前動物的存在(第一句)、部分種類的滅絕(空格前第二句，句中they have no descendants alive now是對extinct一詞的解釋)以及從化石(rocks as fossils)中我們所能發(fā)現(xiàn)的數(shù)百萬年前就死掉了的動物的精確印記(空格后第一句)和當(dāng)時的地貌及氣候特征(空格后第二句)。由此，我們就看到了空格前后兩個句組所敘述內(nèi)容之間的矛盾和內(nèi)容上的不足：1)既然已經(jīng)"滅絕"，怎么還能了解有關(guān)的這一切呢？說明空格前的句子與其空格所在的句子之間具有轉(zhuǎn)折關(guān)系。2)空格后第一句中the rocks指的又是什么石頭呢？需要在前有所提及，即正確選項(xiàng)中應(yīng)包含有rock這個詞。能夠同時滿足這兩個條件的只有選項(xiàng)［B］。 ［A］、［E］、［G］中也提到了rock，但在句際關(guān)系上與前后句組不相吻合，故不正確。所以正確答案只能是［B］。

　　42.【解析】選［F］。文章第一段說明了化石是我們研究史前動物的主要依據(jù)，而本段則主要說明了這些化石的形成�？崭窈�"幾乎我們所知的所有化石都是在由于水作用而形成的巖石中保存下來的 (Nearly all of the fossils that we know were preserved in rocks formed by water action) "一句是一個結(jié)論性表述，之前應(yīng)有"水作用形成的巖石(rocks formed by water action)"這一過程的細(xì)節(jié)描述。［F］的內(nèi)容正好說明死去動物的尸體是如何被水和泥沙保存下來的，與此恰相吻合，所以選［F］。此題極易錯選［G］，因?yàn)椋跥］一開始就有how fossils are preserved，后面又出現(xiàn)了impression一詞，在用詞上出現(xiàn)明顯的復(fù)現(xiàn)現(xiàn)象。 但是［G］后面講的是動物遺體上的有機(jī)組織"organism"可能轉(zhuǎn)化成的幾種形式，這與下文的內(nèi)容不相吻合，故不選［G］。

　　43.【解析】選［E］。本題選擇的線索有兩條：1)空格后有"There were also crab�瞝ike creatures……"，說明空白處應(yīng)有關(guān)于另一類動物的內(nèi)容；2) 從本段開始，文章轉(zhuǎn)向討論由低級向高級進(jìn)化中的動物。［E］開始的部分是"The earliest animals whose remains have been found……"，符合文章寫作的順序。［B］與上文相符，但與下文不符，且與全文結(jié)構(gòu)不相吻合。

　　44.【解析】選［A］。從上一段和本段的 "段際關(guān)系"來看，兩段屬于順接關(guān)系，即兩段在相繼描述兩種不同層級、不同種類的史前動物。從段落結(jié)構(gòu)上來看，兩段的開頭句都是其主題句，下文接著展開進(jìn)行細(xì)節(jié)描述。特別是本段空格后的Of these, ……，標(biāo)志著空格后一句是空格所在句的拓展句。既然下文一開始就有Of these, ……，空白部分就應(yīng)該有"some，several，many"或類似的詞；再者，此段中關(guān)于the ammonites(總類中的一種，考生不必知道其確切含義)的描述，主要闡述了其shell的構(gòu)造，由此說明shell是其主要特征，故在 "總類"的描述(即空缺句)中應(yīng)該含有shell一詞，這就不難判斷答案只能是［A］了。

　　45.【解析】選［C］。此空獨(dú)立成段，所以只能從段際關(guān)系來分析。因?yàn)榍皟啥蚊枋隽耸非皠游镉傻图壪蚋呒壍倪M(jìn)化過程，而此段后就是結(jié)尾段，因此此段必然要起"承上啟下"的作用。所謂 "承上"，是指要對上文進(jìn)行一定的概括、總結(jié)；所謂 "啟下"則是要引出下文。下文中的"reptile"在本題空白處前面的文章中從沒有提到，在下文中又沒有作為新信息，因而作為正確答案的選項(xiàng)中一定有這個詞。［C］從375 million years ago的化石的發(fā)現(xiàn)到300 million years ago的化石的發(fā)現(xiàn)，以及此后nearly 150 million years內(nèi)the reptiles的存在，不但對史前動物的進(jìn)化過程做了很好的概括，而且為下文the Age of Reptile的出現(xiàn)打下了伏筆，是一個很好的"承上啟下"的過渡段，所以正確答案只能是［C］。