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  3. When was the last time you saw a frog? Chances are, if you live in a city, you have not seen one for some time. Even in wet area

When was the last time you saw a frog? Chances are, if you live in a city, you have not seen one for some time. Even in wet area

admin2014-12-31  17
问题     When was the last time you saw a frog? Chances are, if you live in a city, you have not seen one for some time. Even in wet areas once teeming with frogs and toads, it is becoming less and less easy to find those slimy, hopping and sometimes poisonous members of the animal kingdom. All over the world, and even in remote parts of Australia, frogs are losing the ecological battle for survival, and biologists are at a loss to explain their demise. Are amphibians(两栖动物)simply oversensitive to changes in the ecosystem? Could it be that their rapid decline in numbers is signaling some coming environmental disaster for us all? This frightening scenario is in part the consequence of a dramatic increase over the last quarter century in the development of once natural areas of wet marshland-home not only to frogs but to all manner of wildlife. However, as yet, there are no obvious reasons why certain frog species are disappearing from rainforests in Australia that have barely been touched by human hand. The mystery is unsettling to say the least, for it is known that amphibian species are extremely sensitive to environmental variations in temperature and moisture levels. The danger is that planet Earth might not only lose a vital link in the ecological food chain(frogs keep populations of otherwise pestilent insects at manageable levels), but we might be increasing our output of air pollutants to levels that may have already become irreversible. Frogs could be inadvertently warning us of a catastrophe.
    An example of a species of frog that, at far as is known, has become extinct, is the platypus(鸭嘴兽)frog. Like the well-known Australian mammal it was named after, it exhibited some very strange behavior; instead of giving birth to tadpoles in the water, it raised its young within its stomach. The baby frogs were actually born from out of their mother’s mouth. Discovered in 1981, less than ten years later the frog had completely vanished from the crystal clear waters of Booloumba Creek near Queensland’s Sunshine Coast. Unfortunately, this freak of nature is not the only frog species to have been lost in Australia. Since the 1970s, no less than eight others have suffered the same fate.
What is the current situation about the frog extinction in Australia?
选项 A、Eight frog species died out so far in Australia.
B、Biologists explained why frogs are dying elaborately.
C、Frogs are dying out because people destroyed the rainforests in Australia.
D、The marshland is developing quickly these 25 years.
答案D
解析 细节题。根据最后一句话“no less than eight others have suffered the samefate”，可知不少于8种其他物种也灭绝了，故A错误。而第一段的“there are noobvious reasons why certain frog species are disappearing from rainforests in Australia”，说明科学家也不确定为什么有些青蛙灭绝了，B错误。后面的“why certain frogspecies are disappearing from rainforests in Australia that have barely been touched byhuman hand”，可见人们其实并没有破坏青蛙生存的热带雨林，C错误。由“adramatic increase over the last quarter century in the development of once natural areasof wet marshland”，可知沼泽地在这25年一直在发展。故选D正确。
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