首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
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
admin
2011-01-05
71
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.
______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://kaotiyun.com/show/YJVK777K
本试题收录于:
C类竞赛(非英语专业本科)题库大学生英语竞赛(NECCS)分类
0
C类竞赛(非英语专业本科)
大学生英语竞赛(NECCS)
相关试题推荐
(1)Locatedintropicalareaatlowaltitudes,savannas(热带草原)arestableecosystems,somewetandsomedryconsistingofvastg
(1)Preschools—educationalprogramsforchildrenwhoareundertheageoffive—differsignificantlyfromonecountrytoanother
(1)JebBush,whodubbedhimselfa"joyfultortoise"inhispursuitoftheRepublicanpresidentialnomination,hashadenoughof
NewwordsentertheEnglishlanguageallthetime.Infact,Englishhasalwaysbeeninastateof【T1】________.Andinrecentyea
Goodmorning,ladiesandgentlemen.ItiswithagreatpleasurethatIwelcomeyoutothenewMuseumofIndustrialandRuralLif
HowtoWriteResumesPreparations.consideryour【T1】________.decidewhichjobtitlesneedtheskillsandknowledg
Whichoftheitalicizedwordsisdifferentfromtheothers?
TheBottledWaterThebottledwatercanbesourcedfrompublicwatersources,andthepurityandsafetydependlargelyonth
HurricanesWarmwaterandmoist,warmairaretwomainfactorsthatareresponsibleforcausinghurricanestorms.Hurricanes
Whileyou’vebeenlookingatabook,newspaperormagazineinashop,haveyouevertakeaphotowithyourphonesothatyoucou
随机试题
语用的性质包括()
民之穷亦甚矣!树艺畜牧之所得,将以厚其家,而吏夺之。既夺于吏,不敢怨怒。而庶几偿前之失者,望今岁之有秋也,而神复罚之。[亦孔之哀!]嘉谷垂熟,被乎原隰,淫雨暴风,旬月继作,尽扑而捋之。今虽已无可奈何,然遗粒委穗,不当风水冲者,犹有百十之可冀,神曷不亟诉于帝
患者句某,女,3l岁。脘腹胀痛,泄泻不畅,小便短赤,舌苔黄腻,脉沉有力。治宜选用()
提单的收货人栏在填写“Toorderofshipper”内容情况下,提单需要作背书。()
根据下列材料回答问题。CIER指数用来反映就业市场景气程度,其计算方法是:CIER指数=市场招聘需求人数/市场求职申请人数。根据有关机构发布的数据,2018年第一季度CIER指数为1.91,第二季度为1.88,第三季度为1.97,第四季度为2.38。20
中国劳动组合书记部
某厂家生产的一种产品同时在两个市场上销售,售价分别为P1,P2,销售量分别为q1,q2,需求函数分别为q1=24-0.2p1,q2=10-0.05p2,总成本函数为C=35+40(q1+q2),问厂家如何确定两个市场的销售价格,能使其获得总利润最大?最大利
(2009上集管)对于一个新分配来的项目团队成员,______应该负责确保他得到适当的培训。
有以下程序:#includestructS{inta,b;}data[2]={10,100,20,200};main(){struetSp=data[1];printf("
Withthepossibleexceptionofequalrights,perhapsthemostcontroversialissueacrosstheUnitedStatestodayisthedeathpe
最新回复
(
0
)