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
The long, wet summer here in the northeastern U.S.notwithstanding, there’s a world shortage of pure, fresh water.As demand for w
The long, wet summer here in the northeastern U.S.notwithstanding, there’s a world shortage of pure, fresh water.As demand for w
admin
2015-05-29
50
问题
The long, wet summer here in the northeastern U.S.notwithstanding, there’s a world shortage of pure, fresh water.As demand for water hits the limits of finite supply, potential conflicts are brewing between nations that share transboundary freshwater reserves.
Many people ask why we cannot simply take it from the sea, using our sophisticated technology of desalinization.But a good water supply must be hygienically safe and pleasant tasting and water containing salt would corrode machinery used in manufacturing in addition to producing chemical impurities.Since more than 95% of our water sits in the salty seas, man is left to face the reality that most water on the surface of the earth is not available for us.
One very feasible way of sustaining our supply of freshwater is to protect the ecology of our mountains.Mountains and water go together, a fact to which Secretary General Kofi Annan has drawn attention more than once.From 30% to 60% of downstream fresh water in humid areas and up to 95% in arid and semi-arid environments are supplied by mountains.Without interference nature has its own way of purifying water-even though chlorination and filtration are still necessary as a precaution.In a mountainous area, aeration, due to turbulent flow and waterfalls, causes an exchange of gases between the atmosphere and the water.Agriculture, industry, hydroelectric generators and homes that need water to drink and for domestic use depend on these resources and, thus, we must protect mountainous areas as a means of survival.
Streams would purify themselves if not for______.
选项
A、human beings
B、nature
C、chlorination
D、mountains
答案
A
解析
从第3段可知,在没有干预的情况下,大自然用自己的方式净化水源。因此A项为正确答案。
转载请注明原文地址:https://kaotiyun.com/show/CYLO777K
0
考博英语
相关试题推荐
Therangeandvarietyofgovernmentactionthatis,atleastinprinciple,reconcilablewithafreesystemisconsiderable.The
Comparisonsweredrawnbetweenthedevelopmentoftelevisioninthe20thcenturyandthediffusionofprintinginthe15thand1
Fromthehealthpointofviewwearelivinginamarvelousage.Weareimmunizedfrombirthagainstmanyofthemostdangerousd
Academiclifescientistsarecurrentlywell-funded,buttheyneedtodevelopbetteradvocacyskillsinordertoexertsomeinflu
Opinionpollsarenowbeginningtoshowanunwillinggeneralagreementthat,whoeveristo【21】andwhateverhappensfromnowon,
Thepressdemandsthatpoliticians______thesourcesoftheirincome.
Aninvisibleborderdividesthosearguingforcomputersintheclassroomonthebehalfofstudents’careerprospectsandthosea
没有农业,人们就不能生存,社会生产就不能继续下去,因此,农业作为国民经济的基础必须得到足够重视。
Theenergycontainedinrockwithintheearth’scrustrepresentsanearlyunlimitedenergysource,butuntilrecentlycommercial
俗话说,牙疼不是病,但疼起来真要命。前些日子我突然开始牙疼,随便找了点止疼药,希望赶紧止住疼痛。可试了好些天都不管用,最后还是得找牙医。
随机试题
A.年轻恒牙根折B.年轻恒牙冠折牙本质暴露C.乳牙牙齿震荡D.乳牙嵌入E.全脱位半小时的恒牙需氢氧化钙护髓的牙外伤是
A.萎缩型子宫内膜 B.子宫内膜复杂型增生 C.黄体功能不足 D.子宫内膜不规则脱落 E.子宫内膜不典型增生停经3个月后不规则阴道流血2个月,经血量时多时少,常见为
心在体合( )。肝在体合( )。
事业单位设置“财政补助结余”科目,核算事业单位滚存的财政补助项目支出结余资金。()
企业购入的采用权益法核算的长期股权投资,其初始投资成本包括()。
行政法规的地位次于宪法和法律,高于地方性法规、规章。()
已知全集U={x|一1≤x≤4),A={x|一1≤x≤1},B={x|0<0≤3},求∩A.
(2013年福建师范大学)评述梁肩超的教育思想及特点。
设系统中有3种类型的资源(A,B,C)5个进程(P1,P2,P3,P4,P5),A资源的数量是17,B资源的数量是6,C资源的数量为19。在T0时刻系统的状态如下表:系统采用银行家算法实施死锁避免策略,若当前系统剩余资源(A,B,C)别为(2,3,3)
Financialindependence—andconfidence—isanimportantpartofmodernlife.Buthowdoesoneachieveit?Withanincreasingnumbe
最新回复
(
0
)