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
The long, wet summer here in the northeastern U.S. notwithstanding, there’s a world shortage of pure, fresh water. As demand for
admin
2017-08-15
61
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.
By saying that nature "has its own way of purifying water" (Line 5, Para. 3) the author is referring to ______.
选项
A、aeration
B、filtration
C、chlorination
D、absorption
答案
A
解析
本题中大自然净化水源的方式指的是后文提到的充气。因此A项为正确答案。
转载请注明原文地址:https://kaotiyun.com/show/XKFO777K
0
考博英语
相关试题推荐
Everyoneitseemshasahealthproblem.AfterpouringbillionsintotheNationalHealthService,Britishpeoplemoanaboutdirty
Medievalistsusuallydistinguishmedievalpubliclawfromprivatelaw:theformerwasconcernedwithgovernmentandmilitaryaff
IworkasanofficeassistantinasmallbutgrowinggardenequipmentmanufacturingcompanyinCalifornia.Afewmonthsago,my
Shortoftheimpossible,thesatisfactionwegetfromalifetimedependsonhowhighwechooseourdifficulties.
IntheopinionofmanyAmericansandEuropeans,weonlybegantoreallyexploreourworldinthesixteenthcentury.Accordingto
Publicimagereferstohowacompanyisviewedbyitscustomers,suppliers,andstockholders,bythefinancialcommunity,bythe
AfricanAmericanwomen’ssearchforsocietalacceptanceoftenencompassesstrugglebetweennaturalandsociallyconstructedidea
Inthe2006filmversionofTheDevilWearsPrada,MirandaPriestly,playedbyMerylStreep,scoldherunattractiveassistantfo
Everybodylovesafatpayrise.Yetpleasureatyourowncanvanishifyoulearnthatacolleaguehasbeengivenabiggerone.Ind
Inthe2006filmversionofTheDevilWearsPrada,MirandaPriestly,playedbyMerylStreep,scoldherunattractiveassistantfo
随机试题
甲公司采用配股方式进行融资,每10股配2股,配股前股价为6.2元,配股价为5元。如果除权日股价为5.85元,所有股东都参加了配股,除权日股价下跌()。
______是一个能复制一个对象的动画,并应用到其他对象的动画工具。
《医疗机构药事管理暂行规定》的颁布时间为
张某,女,45岁。因胃脘痞闷不适3个月就诊,患者近3个月来经常脘腹痞闷,重时满闷如塞,但不疼痛,饮食减少,恶心嗳气,大便不爽,喜长叹息,有时心烦易怒,胸胁胀满,每因生气恼怒而使症状加重,苔薄白,脉弦。其证型为
可行性研究必须坚持()等原则。
农业税减免包括()、()和()三种形式。
对于证券投资基金来说,其市场参与者有()
基金的流动性风险表现在()。
特别重视强化作用的教学理论流派有()
Archaeologyasaprofessionfacestwomajorproblems.First,itisthepoorestofthepoor.Onlypaltrysumsareavailablefore
最新回复
(
0
)