首页
登录
职称英语
A useful definition of an air pollutant is a compound added directly or indi
A useful definition of an air pollutant is a compound added directly or indi
游客
2024-03-12
24
管理
问题
A useful definition of an air pollutant is a compound added directly or indirectly by humans to the atmosphere in such quantities as to affect humans, animals, vegetation, or material adversely. Air pollution requires a very flexible definition that permits continuous change. When the first air pollution laws were established in England in the fourteenth century, air pollutants were limited to compounds that could be seen or smelled—a far cry from the extensive list of harmful substances known today. As technology has developed and knowledge of the health aspects of various chemicals has increased, the list of air pollutants has lengthened. In the future, even water vapour might be considered an air pollutant under certain conditions.
Many of the more important air pollutants, such as sulphur oxides, carbon monoxide, and nitrogen oxides, are found in nature. As the earth developed, the concentrations of these pollutants were altered by various chemical reactions; they became components in biogeochemical cycles. These reactions serve as an air purification scheme by allowing the compounds to move from the air to the water or soil. On a global basis, nature’ s output of these compounds dwarfs that resulting from human activities. However, human production usually occurs in a localized area, such as a city.
In this localized region, human output may be dominant and may temporarily overload the natural purification scheme of the cycles. The result is an increased concentration of noxious chemicals in the air. The concentrations at which the adverse effects appear will be greater than the concentrations that the pollutants would have in the absence of human activities. The actual concentration need not be large for a substance to be a pollutant; in fact the numerical value tells us little until we know how much of an increase this represents over the concentration that would occur naturally in the area. For example, sulphur dioxide has detectable health effects at 0.08 parts per million(ppm), which is about 400 times its natural level. Carbon monoxide, however, has a natural level of 0.1 ppm and is not usually a pollutant until its level reaches about 15 ppm. [br] It can be inferred from the first paragraph that______.
选项
A、water vapour is an air pollutant in localized areas
B、the definition of an air pollutant will continue to change
C、a substance becomes an air pollutant only in cities
D、most air pollutants today can be seen or smelled
答案
B
解析
细节题。根据文章第一段Air poilution requires a very flexible definition thatpermits continuous change.“空气污染物的定义要求具有灵活性以适应不断的变化”和B选项“空气污染物的定义会继续发生变化”的表达一致。所以答案选B。
转载请注明原文地址:https://tihaiku.com/zcyy/3526316.html
相关试题推荐
Ausefuldefinitionofanairpollutantisacompoundaddeddirectlyorindi
Ausefuldefinitionofanairpollutantisacompoundaddeddirectlyorindi
Ausefuldefinitionofanairpollutantisacompoundaddeddirectlyorindi
Althoughrecentyearshaveseensubstantialreductionsinnoxiouspollutants
[originaltext]W:Doyouthinkyoucangiveanexactdefinitionof"management",
[originaltext]W:Doyouthinkyoucangiveanexactdefinitionof"management",
[originaltext]W:Doyouthinkyoucangiveanexactdefinitionof"management",
[originaltext]W:Doyouthinkyoucangiveanexactdefinitionof"management",
[originaltext]Recently,twoleadingheartorganizationschangedthedefinition
[originaltext]Recently,twoleadingheartorganizationschangedthedefinition
随机试题
“那达慕”(Nadama)是蒙古语,意为“娱乐、游戏”,还可以表示人们丰收的喜悦之情。"Nadama"comesfromMongolianlanguag
Listentothefollowingpassage.WriteinEnglishashortsummaryofaround150-
[originaltext]TheInternationalAtomicEnergyAgencysaysU.S.EnergySecret
Iaskedsuccessfulpeoplewhatthesecretoftheirsuccesswas.I【B1】______
下列脉象不属于阴的是A.浮 B.涩 C.以上都不是 D.沉 E.迟
根据《企业会计准则》规定,属于职工范围的是( )。 Ⅰ.与企业订立了无固定期
关于MMPI,下列说法中正确的是()。 (A)分为手册式和卡片式两种主
某公司一次到货一批进口木材,分属甲(一般贸易合同)、乙(加工贸易合同)两个合同项
某生产性建设项目,生产某单一产品,设计生产能力为16000件,年固定成本为120
下列表达式正确的有( )。A.速动比率=速动资产/流动负债 B.总资产净利率=
最新回复
(
0
)