首页
登录
职称英语
[img]2012q2/ct_eyyjscz2008b_eyyjscreadb_0021_20121[/img] When was the last t
[img]2012q2/ct_eyyjscz2008b_eyyjscreadb_0021_20121[/img] When was the last t
游客
2024-08-18
46
管理
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, even in remote jungles on the far side of the globe, frogs are losing the ecological battle for survival, and biologists are at a loss to explain their demise. Are amphibians
simply over-sensitive to changes in the ecosystem? Could their rapid decline in numbers be signalling some coming environmental disaster for us all?
This frightening scenario is in part the consequence of a dramatic increase over the last quarter of a century in the development of once natural areas of wet marshland; home not only to frogs but to all manner of wildlife. Yet, there are no obvious reasons why certain frog species are disappearing from rainforests in the Southern Hemisphere which are barely touched by human hands. 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 bizarre occurrence regarding a species of frog dates from the summer of 1995 , when "an explosion” of multi-coloured frogs of the species Rana klepton esculenta occurred in the Netherlands. Normally these frogs are brown and greenish-brown, but some unknown contributory factor is turning these frogs yellow and / or orange. Nonetheless, so far, the unusual bi- and even tri-coloured frogs are functioning similarly to their normal-skinned contemporaries. It is thought that frogs with lighter coloured skins might be more likely to survive in an increasingly warm climate due to global warming.
One theory put forward to explain extinct amphibian species that seems to fit the facts concerns the depletion of the ozone layer, a well-documented phenomenon which has led to a sharp increase in ultraviolet radiation levels. The ozone layer is meant to shield the Earth from UV rays, but increased radiation may be having a greater effect upon frog populations than previously believed. Another theory is that worldwide temperature increases are upsetting the breeding cycles of frogs. [br] ______has led to a sharp increase in ultraviolet radiation levels.
选项
答案
The depletion of the ozone layer
解析
(最后一段明确提到…the depletion of the ozone layer,a well-documented phenomenon which has led to a sharp increase in ultraviolet radiation levels。)
转载请注明原文地址:https://tihaiku.com/zcyy/3725212.html
相关试题推荐
[img]2012q2/ct_eyyjsdz2009b_eyyjsdreada_0292_20121[/img]Doyoueverwonder
[img]2012q2/ct_eyyjsdz2009b_eyyjsdreada_0292_20121[/img]Doyoueverwonder
[img]2012q2/ct_eyyjsdz2009a_eyyjsdreada_0219_20121[/img]Theopeningofyour
[img]2012q2/ct_eyyjsdz2009a_eyyjsdreada_0219_20121[/img]Theopeningofyour
[img]2012q2/ct_eyyjsdz2009a_eyyjsdreada_0219_20121[/img]Theopeningofyour
[img]2012q2/ct_eyyjsdz2009a_eyyjsdreada_0219_20121[/img]Theopeningofyour
[img]2012q2/ct_eyyjsdz2009a_eyyjsdreada_0219_20121[/img]Theopeningofyour
[img]2012q2/ct_eyyjsdz2009a_eyyjsdreada_0219_20121[/img]Theopeningofyour
[img]2012q2/ct_eyyjsdz2010b_eyyjsdreada_0162_20121[/img]Manyculturesfollo
[img]2012q2/ct_eyyjsdz2010b_eyyjsdreada_0162_20121[/img]Manyculturesfollo
随机试题
Americansstillfollowmanyoftheoldways.Youngpeoplestillgetmarried.
某高层建筑外设有消防水池,消防水池上设有供消防车取水的取水口,取水口与建筑的距离
下列各项中,不符合内部牵制的要求的是()。A、出纳人员管票据 B、出纳人员
A.块状冲剂B.酒溶性颗粒剂C.水溶性颗粒剂D.混悬性颗粒剂E.泡腾性颗粒剂将处
根据有关规定,可以发布房地产广告的是()。A.在集体土地上建设的房屋 B.
流行语是人们社会生活的直接反映,折射出时代的色彩。就像“电”派生出一批带“电”词
2020年,我国粮食种植面积11677万公顷,比上年增加70万公顷。其中,稻谷种
鱼塘边工厂仓库着火,甲用水泵从乙的鱼塘抽水救火,致鱼塘中价值2万元的鱼苗死亡。仓
请根据所提供的单据判断填制《入境货物报检单》有关内容的正误(见报检单上标注的题号
下列各项中,属于会计估计变更的有( )。A.长期股权投资的核算因增加投资份额由
最新回复
(
0
)