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Reading Passage 2 |
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Title: |
鱷魚的進(jìn)化the crocodile’s evolution |
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Question types: |
段落大意 Heading 填空 配對 |
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文章內(nèi)容回顧 |
詳細(xì)講述了crocodiles的生活習(xí)慣，如何控制自己的溫度以及喜歡的生存環(huán)境等。包括提到鱷魚的特點(diǎn)、歷史以及對兩組處在不同水供給環(huán)境下的生存情況對比。 舊文P2=V09121 |
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英文原文閱讀 |
Early and extinct forms of crocodiles are called Crocodilia. They descended from psuedosuchians who walked on their hind legs, and lived during the late Triassic period. The skull of the crocodile still resembles in many ways those of the primitive archosaurs. Their bodies, however, developed the external appearance of the phytosaurs because of their aquatic lifestyle. The crocodile is the only archosaur that survived the still unknown factors that wiped out most of the reptile class at the end of the Mesozoic period. Though modern crocodiles walk on 4 legs, their two legged ancestry is revealed by their hind legs which are longer than the front legs, making them slant forward when they stand. The crocodilian skull still carries a basically archosaurean shape. It has a rather long, pointed skull, especially in the fish eating species of crocodiles. The biggest, most prominent change in the crocodile since its early days is to the palate. The palate is the flat bony part at the roof of the mouth. In phytosaurs, the nostril holes in the palate are located under the outer nostrils, which were shifted to the far back of their snout. However in crocodiles, the nostrils are located at the front of the snout. This caused a problem in keeping the breathing passages from filling with water. Millions of years of evolution solved this problem. A second palate was formed, channeling the air above the mouth and into the throat passageway, where it can be opened and closed by a special flap or valve of skin. Crocodiles are actually classified on the basis of how far back their secondary palate extends, ranging from those who have no secondary palate to those with a fully formed palate separating the air they breathe from the water in their mouths. The first crocodilians were called Protosuchians, living during the late Triassic to early Jurassic times. The difference between these and modern crocodiles is in the legs. The Protosuchians had very strong overdeveloped legs, which were set at right angles to the body. These allowed the animal to carry itself higher off the ground and probably gave them much more speed than their modern day counterparts. These legs also lead scientists to believe that these reptiles mostly lived on land. Beginning in the Jurassic period, the crocodilians quickly filled the gap of the extinct phytosaurs, becoming large and fully aquatic reptiles. The Mesosuchians were the next evolution of the protosuchians and lived during the Jurassic period and beyond. These reptiles had not yet developed a secondary palate, but were much more adapted to aquatic life than its predecessor. They had strong armor plating, made from a series of paired large bones on their back with smaller plates on its undersides. They spread throughout the land and lived in fresh water, though some adapted for sea life. These were called Geosaurs. Geosaurs lost their bony armor, their legs modified into paddles and their tail tips turned down, similar to the ichthyosaurs. Our modern crocodile appeared during the Cretaceous period, living side by side with the Mesosuchiansun until they were displaced in the early Tertiary times. |
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題型難度分析 |
Heading題考察skim能力，難度不大，但得分率不高。 |
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題型技巧分析 |
標(biāo)題配對題（List of headings）是雅思閱讀中的一種重要題型，要求給段落找小標(biāo)題。它一般位于文章之前，由兩部分組成：一部分是選項(xiàng)，另一部分是段落編號，要求給各個(gè) 段落找到與它對應(yīng)的選項(xiàng)，即表達(dá)了該段中心思想的選項(xiàng)，有時(shí)還會舉一個(gè)例子。當(dāng)然，例子中的選項(xiàng)是不會作為答案的。 解題思路： 1. 將例子所對應(yīng)的選項(xiàng)及段落標(biāo)號劃去 2. 劃出選項(xiàng)中的關(guān)鍵詞及概念性名詞 3. 瀏覽文章，抓住各段的主題句和核心詞（尤其是反復(fù)出現(xiàn)的核心詞），重點(diǎn)關(guān)注段落首句、第二句與末句 4. 與段落主題句同義或包含段落核心詞的選項(xiàng)為正確答案 |
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