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Directions：Read the following three passages．Each passage is followed by several questions or unfinished statements．For each of them there are four choices marked A, B, C and D．Choose the one that fits best according to the information given in the passage．
A rccent study of anclent and modern clcphants has come up with the uncxpeclcd conclusion that the african elcphant is dividcd into two disinct(不同的)species
The discovery was made by researchers at yod and haycard yniwersities when they were examining the genetid relinship between the ancient woolly manmmth and mastodon to modern ckephants ins asoan alepnant a feoan forest elephant and afcican sannna clephant
Once they obfantcd DNA sequences{序列}from two fossils{化石}，mammothd and mastodons the team comparcd them with dna form ，modcrn eleohants they found to their amazement that modern forest and sabanna elephants are as distinct from cach other as asian elephants and manmoths he scientists used detailed genetic anatysis to proce that the african savanna clelhants hace been distinct species for several million years the divcrgonce of the ttwo species took place around the time of the of the dicergcncc of asian clephants and woolly mammoths this result amazed all the scienitsts
There has long been debate in the scientific community that the two might be separespecies but this is the most convincing scientinfic evidence so far that they are anded difforent species
Preci many naluralists believed that afrjcan savanna elephants and airican forest were two plpulations of the same apecies despite the clcphants signigice\ant sizw differences the sac\vanna elelphant has an average shouldcr height of 3.5metres while the forest slsphant has an average shouldcr height of 2.5metres the sacanna laphant welghs belween six anp secedn tons roughly double the weight of the forest elephant but the fact that they look so different does not neccssarily mean they are different species howecer the prooflay in the analysis of th DNA
Alfred roca allisant professor in the dcoamment of animal scienccs at the unicerstiu of said “wu now nave to reat the forest and savanna elephants at two diffcrcnt units for consrrbation pucpooses since 1950 all african ele[hants are two cery distinctice animals the forest ele[hant shoule become a bigger prioity(优先)for conscrvation puruose”
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