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
Water will evaporate from any wetted surface. A .significantly large fraction of the rainfall that falls on land is returned to
Water will evaporate from any wetted surface. A .significantly large fraction of the rainfall that falls on land is returned to
admin
2011-04-26
45
问题
Water will evaporate from any wetted surface. A .significantly large fraction of the rainfall that falls on land is returned to the atmosphere in this fashion. In addition water is assimilated by root systems of growing plants and is later transpired from the leaf surfaces by a process essentially identical to evaporation. The two effects, evaporation and transpiration, cannot be individually discriminated for their effectiveness in returning rainfall to the atmosphere, but their sum contribution can be evaluated and is usually called the evapotranspiration factor. The fraction of rain falling on the United States that is returned to the atmosphere by evapotranspiration, for example, is 70 percent; for the world as a whole, approximately 62 percent. In arid countries such as Australia the fraction is larger, and in less arid areas such as the United Kingdom it is lower. Water returned to the atmosphere by evapotranspiration is unavailable to man, except in, the sense that useful plants may be grown in the place of useless ones. It cannot be trapped and redistributed for industrial or other purposes.
In regions of low rainfall, plant cover will develop to a point where all precipitation is used in evapotranspiration and none remains for stream now. Seasonal rainfalls provide a qualifier for this statement because streams will flow even in the most arid areas during periods of maximum rainfall. In general, if the potential evapotranspiration—that which would result from the maximum plant cover a region could support under ideal circumstances—should exceed the precipitation, overland stream flow ceases. Conversely, if evapotranspiration is less than precipitation, runoff is generated.
The amount by which precipitation exceeds evapotranspiration is the perennial yield of stream flow water, and this is the usable fraction of rain and snowfall. Across the entire United States the water yield amounts to 30 percent of the total rainfall, or approximately 1.77×1015 liters per year. But when we consider the distribution of water deficiencies and surpluses we find that essentially the entire eastern half of the United States, together with a small region in the Pacific northwest, enjoys water surplus, while most of the country to west of the Mississippi is water- deficient and arid.
It can be inferred from the passage that ______.
选项
A、more than 30% of total rainfall can yield stream flow in the United States
B、the water in the entire eastern haft of U. S.A. goes beyond its necessary need
C、west part of U. S. A.doesn’t have perennial yield of stream flow water
D、the yield of stream flow water is ’unevenly distributed in the United States
答案
D
解析
转载请注明原文地址:https://kaotiyun.com/show/zo6O777K
0
考博英语
相关试题推荐
Readthefollowingpassage.Arethesentences(16-22)"Right"or"Wrong"?Ifthereisn’tenoughinformationtoanswer"Right"or
ReadtheChairman’sStatementbelowandanswerquestions23—28.Forquestions23—28,choosethecorrectanswer.Foreachq
Dysonvacuumcleanersarenotlikeothercleaners.DesignandengineeringareseparatedepartmentsatDyson.
Readthememosbelow.Completetheconferencebookingformontheoppositepage.Writeawordorphrase(inCAPITALLETTERS)ora
Readtheadvertisementbelowforahotdrinksmachine.Aresentences16-22"Right"or"Wrong"?Ifthereisnotenoughinform
Readthefollowingminutesofameeting.Aresentences16-22ontheoppositepage’Right’or’Wrong’?Ifthereisnotenough
Amsterdam--NewYorkTwiceWeeklyComfortablebyAirbus-310inFirst,BusinessorEconomyClass______.
Readthearticlebelowaboutstaffsurveys.ChoosethecorrectwordtofilleachgapfromA,BorContheoppositepage.Fo
TheJapanesePrimeMinister’s______isaseatontheUNSecurityCouncil,forwhichhewillbelobbyingatthesummit.
Hershabbyclotheswereoftenmade______byherclassmates.
随机试题
Whatisthe’biggestcityintheworld?Thatis,【21】cityhasthelargestpopulation?Thisseemslike【22】questiontoanswer,but
影响酶促反应速度的因素不包括
关于健康危险因素评价的描述,正确的是
1999年4月南方某大型湖泊1800亩水面泛起了一片片死鱼,湖水呈黑色,空气中弥漫着难闻的臭味,使人感到呼吸困难,头昏、恶心等。首先应考虑作的检测项目是
施工企业年度安全生产管理目标出台后,企业主要负责人应明确专人,根据企业安全生产责任制的要求,将目标分解到()。
根据《中华人民共和国城乡规划法》的规定,下列关于城乡规划的编制和审批程序的表述中不正确的是()。
背景:某建设单位新建办公楼,与甲施工单位签订施工总承包合同。该工程门厅大堂内墙设计做法为干挂石材,多功能厅隔墙设计做法为石膏板骨架隔墙。施工过程中发生下列事件:事件一:建设单位将该工程所有门窗单独发包,并与具备相应资质条件的乙施工单位签订门窗施工合同。
工程项目安全检查的注意事项包括( )。
对直接用于出售的存货和用于继续加工的存货,企业在确定其可变现净值时应当考虑不同的因素。()
当动物缺乏某激素时,可以通过“饲喂法”或“注射法”对该激素进行人为补充,下列只可通过以上一种方法补充的激素是()。①生长激素②甲状腺激素③胰岛素④性激素
最新回复
(
0
)