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
Frog 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
Frog 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
admin
2010-04-12
62
问题
Frog
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 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, as far as is known, has become extinct, is the platypus 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.
One theory 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.
Frogs are important in the ecosystem because they control pests.
选项
A、Y
B、N
C、NG
答案
A
解析
依据文章第一段倒数第二句不难看出,青蛙由于可以吃掉害虫,因而在生态系统的食物链中非常重要。
转载请注明原文地址:https://kaotiyun.com/show/lfj7777K
0
大学英语四级
相关试题推荐
A、Hedidnotspendmoneyfreely.B、Hewasalwayswell-dressed.C、Hehadaluxuriousear.D、Heworkedhardforaliving.A信息明示题,文
Eachofusseeksourownpathtobliss(幸福).InacceptingtheNobelPrizefromtheSwedishKingin1980,IsaidthatIhadbeen
A、Becausehedoesn’twanttomakealivinglikeordinarypeople.B、Becauseonlytheprisoncanhelphimtocontrolhimself.C、Be
HarryPotterhasbewitcheddetainees(未判决囚犯)attheU.S.prisonatGuantanamoBay,theretalesoftheyoungwizardand
A、Youvastlyincreasethechancesforasuccessfulhire.B、Youwillbemorefamiliarwiththepersonyouhire.C、Youcanidentif
A、Dutiesandfurthereducation.B、Chancestotravel.C、Desiredsalary.D、Promotioninyourjob.A短文最后提到面试者可以问的话题,其中包括duties和furt
AftertheviolentearthquakethatshookLosAngelesin1994,earthquakescientistshadgoodnewstoreport:Thedamageanddeath
AftertheviolentearthquakethatshookLosAngelesin1994,earthquakescientistshadgoodnewstoreport:Thedamageanddeath
StudentswhowanttostudyintheUnitedStatesmayfindthattheirchancesforfinancialaidarelimited.Theyoftenhavetopa
EarthquakeCanScientistsPredictKillerEarthquakes?ThedatewasNovember23,1980.PeoplenearNaples,inSouthernItaly
随机试题
劳动合同的解除
为总分类科目“应收账款”设置明细分类科目时,一般所采用的设计依据是按________。
A、cloudyB、captainC、certainD、cottonCA,B,D项划线部分发[k],C项划线部分发[s],因此选C项。
下列选项中,不属于该类药物的是
感染性休克治疗错误的是
与尿石症病机关系最密切的是
下列哪一项不属于基金销售机构的准人条件?()
由于发展受挫而产生轻视自己的情绪属于()
Itwasa(n)________thing—itmadethehaironthebackofmyneckstandup.
A、Lessthan40minutes.B、From40to70minutes.C、Atleast40minutes.D、Morethan70minutes.BHowlongdoesaninterviewusua
最新回复
(
0
)