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
60
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.
One danger to the Earth because of decreasing frog numbers is that we may______in the ecological food chain.
选项
答案
lose a vital link
解析
(第二段提到蛙类数量减少的危害之一是地球lose a vital link in the ecological food chain。)
转载请注明原文地址:https://kaotiyun.com/show/aJVK777K
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)SANFRANCISCO—Aftermonthsoffeverishspeculation,StevenP.JobsintroducedWednesdaywhatApplehopeswillbethecoole
Thisisapicture.Inthe【T1】________,thereisahousebuiltintothesideofabarehill.Thehouseisactuallycutoutofthe
Goodmorning,ladiesandgentlemen.ItiswithagreatpleasurethatIwelcomeyoutothenewMuseumofIndustrialandRuralLif
A、BecauseShakespeareanEnglishisclosertomodernEnglish.B、BecauseShakespeareanEnglishisspokenbyalotofpeople.C、Bec
A、Becauseshewasbusywithherstudy.B、Becauseshewasillinbed.C、Becauseshedidn’tknowtherewassuchatour.D、Because
A、Becausemostchildrenhaveneverbeentoschoolandawayfrommommyforlong.B、Becauselessonsinkindergartenaretoodiffic
Britain’spressisunusual________itisdividedintotwoverydifferenttypesofnewspaper:thequalitypressandthepopularpr
TheBottledWaterThebottledwatercanbesourcedfrompublicwatersources,andthepurityandsafetydependlargelyonth
Wheredoesthisconversationprobablytakeplace?
Ifyou【D1】______smoothskinthatglowswithyouth,thechancesarethatatsomepointyouwillhaveheardtheexhortationtodri
随机试题
丽芬是一位普通的农村妇女。丈夫长年在外打工。很少回家,还经常抽烟喝酒,每年拿不了多少钱回家。丽芬除了种地、养猪、养牛之外,还要照顾上学的女儿以及多病的婆婆,是家庭的经济支柱。婆婆和丈夫都希望丽芬再生一个男孩。可丽芬自己不想再生第二胎,也一直没有怀上。因此,
HAyEm稀释液中,氯化钠的主要作用是
气虚型子宫脱垂的首选方是
某银行与某投资商签订了担保合同,双方当事人没有约定保证方式,此时应按照()。
下列关于子女教育支出扣除规定的表述,错误的是()。
xBRL(可扩展商业报告语言)的作用很广泛,企业的各种信息,特别是财务信息,都可以通过xBRL在计算机互联网上有效地进行处理。信息发布者一旦输人了信息,就无需再次输入,通过xBRL就可以很方便地转换成书面文字,PDF文件,或者其他相应的文件格式。而且,通过
患者,女,54岁,胆源性胰腺炎发作数次,对预防其胰腺炎再次发作最有意义的措施是()。
下列家庭教育做法中,做法不合理的是()
下列各句中,没有语病的一句是()
Infact,PeterwouldratherhaveleftforSanFranciscothan______inNewYork.
最新回复
(
0
)