Question

15．A recent study of ancient and modem elephants has come up with the unexpected conclusion that the African elephant is divided into two distinct（不同 的）species．
     The discovery was made by researchers at York and Harvard Universities when they were examining the genetic relationship between the ancient woolly mammoth and mastodon to modem elephants-the Asian elephant，African forest elephant，and African savanna elephant．
     Once they obtained DNA sequences（序列）from two fossils（化石），mammoths and mastodons，the team compared than with DNA from modem elephants．They found to their amazement that modem forest and savanna elephants are as distinct from each other as Asian elephants and mammoths．
     The scientists used detailed genetic analysis to prove that the African savanna elephant and the African forest elephant have been distinct species for several million years．The divergence of the two species took place around the time of the divergence of Asian elephants and woolly mammoths．This result amazed all the scientists．
    There has long been debate in the scientific community that the two might be separate species，but this is the most convincing scientific evidence so far that they are indeed different species．
    Previously，many naturalists believed that African savanna elephants and African forest elephants were two populations of the same species，despite the elephants'significant size differences．The savanna elephant has an average shoulder height of 3.5 metres while the forest elephant has an average shoulder height of 2.5 metres．The savanna elephant weighs between six and seven tons，roughly double the weight of the forest elephant．But the fact that they look so different does not necessarily mean they are different species．However the proof lay in the analysis of the DNA．
     Alfred Roca，assistant professor in the Department of Animal Sciences at the University of Illinois，said，"We now have to treat the forest and savanna elephants as two different units for conservation purposes．Since 1950，all African elephants have been conserved as one species．Now that we know the forest and savanna elephants are two very distinctive animals，the forest elephant should become a bigger priority（优先）for conservation purposes．"
46．One of the fossils studied by the researchers is that ofD．
A．the Asian elephant                       B．the forest elephant
C．the savanna elephant                     D．the mastodon elephant．
47．The underlined word"divergence"in Paragraph 4 means"C．"
A．evolution      B．exhibition             C．separation       D．examination
48．The researchers'conclusion was based on a study of the African elephantsA
A．DNA        B．height                 C．weight          D．population
49．What are Alfred Roca's words mainly about？A
A．The conservation of African elephants．
B．The purpose of studying African elephants．
C．The way to divide African elephants into two units．
D．The reason for the distinction of African elephants．
50．Which of the following can be the best title for the passage？C
A．Naturalists'Beliefs about Elephants
B．Amazing Experiments about Elephants
C．An Unexpected Finding about Elephants
D．A Long Scientific Debate about Elephants．

Answer 1

分析 最近的一项究表明非洲大象被分为两种截然不同的物种．对不同的非洲大象要分别采取不同的保护措施．

解答 46．D 细节理解题．根据第三段的第一句Once they obtained DNA sequences（序列）from two fossils（化石），mammoths and mastodons…可知答案为D
47．C词义猜测题．前面一句讲到了这两种大象分离成不同的物种已有数百万年了，由此可判断divergence在此是"分离"之意．
48．A细节理解题．根据倒数第二段的最后一句可知研究人员的结论是在检测非洲大象DNA的基础上得出来的．
49．A推理判断题．根据最后一段的内容可知Alfred Roca的话主要讲的是对不同的非洲大象要分别采取不同的保护措施．
70．C主旨大意题．根据本文的主题句（第一段）A recent study of ancient and modem elephants has come up with the unexpected conclusion that the African elephant is divided into two distinct（不同 的）species，最近的一项究表明非洲大象被分为两种截然不同的物种可知选C

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