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
Where Have All the Frogs Gone? In the 1980s, scientists around the world began to notice something strange: Frogs were disapp
Where Have All the Frogs Gone? In the 1980s, scientists around the world began to notice something strange: Frogs were disapp
admin
2009-06-15
87
问题
Where Have All the Frogs Gone?
In the 1980s, scientists around the world began to notice something strange: Frogs were disappearing. More recent research has shown that many kinds of amphibians (两栖动物) are declining or have become extinct. They have been around for a long time - over 350 million years. Why are they dying out now?
Scientists are seriously concerned about this question. First of all, amphibians are an important source of scientific and medical knowledge. By studying amphibians, scientists have learned about new substances that could be very useful for treating human diseases. Further research could lead to many more discoveries, but that will be impossible if the amphibians disappear.
The most serious aspect of amphibian loss, however, goes beyond the amphibians themselves. Scientists are beginning to think about what amphibian decline means for the planet as a whole. If the earth is becoming unlivable for amphibians, is it also becoming unlivable for other kinds of animals and human, beings as well?
Scientists now believe that amphibian decline is due to several environmental factors. One of these factors is the destruction of habitat, the natural area where an animal lives. Amphibians are very sensitive to changes in their habitat. If they cannot find the right conditions, they will not lay their eggs. These days, as wild areas are covered with houses, roads, farms, or factories, many kinds of amphibians are no longer laying eggs. For example, the arroyo toad (蟾蜍) of southern California will only lay its eggs on the sandy bottom of a slow-moving stream. There are very few streams left in southern California, and those streams are often muddy because of building projects. Not surprisingly, the arroyo toad is now in danger of extinction.
There are a number of other factors in amphibian decline. Pollution is one of them. In many industrial areas, air pollution has poisoned the rain, which then falls on ponds and kills the frogs and toads that live there. In farming areas, the heavy use of chemicals on crops has also killed off amphibians. Another factor is that air pollution has led to increased levels of ultraviolet (UV) light. This endangers amphibians, which seem to be especially sensitive to UV light. And finally, scientists have discovered a new disease that seems to be killing many species of amphibians in different parts of the world.
All these reasons for the disappearance of amphibians are also good reasons for more general concern. The destruction of land, the pollution of the air and the water, the changes in our atmosphere, the spread of diseases - these factors affect human beings, too. Amphibians are especially sensitive to environmental change. Perhaps they are like the canary (金丝雀) bird that coal miners once used to take down into the mines to detect poisonous gases. When the canary became iii or died, the miners knew that dangerous gases were near and their own lives were in danger.
选项
A、knowledge about fatal human diseases.
B、knowledge about air and water pollution.
C、a chance to discover new medicines.
D、an opportunity to detect poisonous gases.
答案
C
解析
转载请注明原文地址:https://kaotiyun.com/show/w2Ld777K
本试题收录于:
职称英语理工类A级题库职称英语分类
0
职称英语理工类A级
职称英语
相关试题推荐
ScientistsDevelopWaysofDetectingHeartAttackGermanresearchershave(1)anewgenerationofdefibrillatorsandearlywarn
LookingtotheFutureWhenamagazineforhigh-schoolstudentsaskeditsreaderswhatlifewouldbelikeintwentyyears,the
Thefoodisinsufficientforthreepeople.
TheproblemfacingBritishsurgeonsintheearly19thcenturywasthatBurkeandHaredifferedfromotherbodysnatchersintha
WhatIsAnthrax?There’sbeenalotoftalkaboutanthraxonthenewslately.Somepeoplearewordedthatanthraxmaybeconn
TheDangersofSecondhandSmokeMostpeopleknowthatcigarettesmokingisharmfultotheirhealth.Scientificresearchshows
WhyDoManyFemaleAthletesFallVictimtoKneeInjuries?RebeccaLobo,abasketballstar,grabbedareboundduringthefirst
TheFoodScandalWidensAsthescopeofthefoodscandalwidensinTaiwan—morethan200firmsand500productshavebeeninv
Anoysterproducesapearlbycoatingagrainofsandinsideitsshellwithnacre,asecretionofitsbody.
WhydoestheauthorthinktheEiffelToweristransformedintosymbolofaworldonthemove?WhichstatementisNOTtrueofHu
随机试题
影响环境稳定的因素不包括()
某出口商以电报形式向进口商发盘,但在发盘到达进口商之前又以传真告知进口商此发盘无效,此行为属于
像饼图一样,圆环图也显示了部分与整体的关系,但圆环图可以包含多个数据系列。在该类型中有:______,______。
猝死
患者,男性,35岁。一年前开始出现低热、乏力,近半年来逐渐出现四肢关节与肌肉酸痛,举手及登楼困难,同时在眼睑、鼻梁、远端指间关节及甲周围皮肤出现暗红色斑。根据上述检查,给予糖皮质激素治疗,疗程一年半,患者上述症状无改善,肌无力更加严重,行走困难,但肌酶
下列属于内部控制基本要素的是( )。
丁公司2015年12月31日的资产负债表显示,资产总额年初数和年末数分别为4800万元和5000万元,负债总额年初数和年末数分别为2400万元和2500万元,丁公司2015年度营业收入为7350万元,净利润为294万元。要求:计算销售净利率。
请回答下列问题:光反应中能把光能转换成电能的叶绿素是少数处于特殊状态的______。
在中国历史上曾经出现过成康之治、文景之治、贞观之治、康乾之治等所谓盛世。盛世的出现是和法制的相对健全分不开的,法制是推动盛世出现的条件,又是盛世的外在标志。从来没有无法制的盛世,也从来没有盛世而法制衰微的现象。即使是入主中原的少数民族,在立定脚跟之后也急于
根据下面材料回答问题。2012年上半年,石油和化工行业规模以上企业累计总产值5.89万亿元,同比增长12.5%;利润总额3535.4亿元,同比下降15.9%;主营业务收入5.60万亿元,同比增长10.4%;资产总计8.10万亿元,同比增长12.8
最新回复
(
0
)