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
2024-04-21
30
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/3565622.html
相关试题推荐
Ausefuldefinitionofanairpollutantisacompoundaddeddirectlyorindi
Ausefuldefinitionofanairpollutantisacompoundaddeddirectlyorindi
Althoughrecentyearshaveseensubstantialreductionsinnoxiouspollutants
Althoughrecentyearshaveseensubstantialreductionsinnoxiouspollutants
Althoughrecentyearshaveseensubstantialreductionsinnoxiouspollutants
Althoughrecentyearshaveseensubstantialreductionsinnoxiouspollutants
Althoughrecentyearshaveseensubstantialreductionsinnoxiouspollutants
Althoughrecentyearshaveseensubstantialreductionsinnoxiouspollutants
Ausefuldefinitionofanairpollutantisacompoundaddeddirectlyorindi
Ausefuldefinitionofanairpollutantisacompoundaddeddirectlyorindi
随机试题
夜是安静的,然而也是生动的。狗儿活跃起来了,它们悄然无声地沿着院子围墙跑着,不时地停下来支支耳朵,细察来自远近的一切动静,履行保卫主人的职责。鼠儿活跃起
Thebiggestsafetythreatfacingairlinestodaymaynotbeaterroristwith
TheBirthofScientificEnglishA)Worldscienceisdominate
Themanagerurgedthathisstaff__________(不要错过这个机会).(should)notdrop/missthe
依靠人的知识和经验,对事物变化发展的趋势作出定性的描述,这就是经济预测。它往往用
SCL-90不适用于()。 (A)诊断求助者的各类心理疾病(B)了
甲普通合伙企业的合伙人赵某欠个体工商户王某10万元债务,王某欠甲合伙企业5万元债
下列房地产市场预测方法中,属于定量预测的有()。 A.时间序列法 B.回归
某企业计提生产车间管理人员基本养老保险费120000元。下列各项中,关于该事
财产清查中,对发现的确实无法支付的应付账款经批准后应转入“营业外收入”账户处理。
最新回复
(
0
)