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
2023-08-04
43
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 materials 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 vapor might be considered an air pollutant under certain conditions.
Many of the more important air pollutants, such as sulfur oxides (硫氧化物), 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 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 effect appears 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, sulfur dioxide has detectable health effects at 0. 08 parts per million (ppm), which is about 400 times its natural level. Carbon monoxide, however, has natural level of 0. 1 ppm and is not usually a pollutant until its level reaches about 15 ppm. [br] From the first paragraph, we can infer that________.
选项
A、water vapor is an air pollutant in localized areas
B、today most air pollutants can be seen or smelled
C、the definition of air pollution will continue to change
D、a substance becomes an air pollutant only in cities
答案
C
解析
由题干关键词the first paragraph定位至第一段。推理判断题。由第一段第二句可知,C“空气污染的定义会继续改变”与文章表述一致,而且文中也详细说明了这一变化情况,故C为正确答案。
转载请注明原文地址:https://tihaiku.com/zcyy/2895916.html
相关试题推荐
[originaltext]W:Doyouthinkyoucangiveanexactdefinitionof"management",
Ausefuldefinitionofanairpollutantisacompoundaddeddirectlyorindi
Ausefuldefinitionofanairpollutantisacompoundaddeddirectlyorindi
Ausefuldefinitionofanairpollutantisacompoundaddeddirectlyorindi
[originaltext]Researchershaveidentifiedapotentnewantibioticcompound
[originaltext]Researchershaveidentifiedapotentnewantibioticcompound
[originaltext]Researchershaveidentifiedapotentnewantibioticcompound
[originaltext]Researchershaveidentifiedapotentnewantibioticcompound
[originaltext]Researchershaveidentifiedapotentnewantibioticcompound
Thermoelectricmaterialscanconvertwasteheatdirectlyintoelectricity.T
随机试题
Thefitnessmovementthatbeganinthelate1960sandearly1970scentered
Asuperstar【B1】______issomeonewhohasbecomefamousinsports,orfilms,
【B1】[br]【B14】A、doB、haveC、areD、thoseCthan这个词之前和之后的结构应该是对等的;由于前文使用了be动词的结构,所
下列关于注册商标的许可使用说法错误的有()。A.商标注册人是许可人 B.商
燥邪伤人最易伤及人体的哪个脏腑A.肺 B.脾 C.心 D.肾 E
有句俗话叫“要想身体好,天天吃核桃”,多年经验浓缩成的俗话一定有它的道理,最近,
物流外包是企业常用的做法。对货主企业而言,外包的缺点是()。A:不利于有效利用资
下列有关月平均人数的公式最精确的是()A.月平均人数=(月初人数+月末人数)/
设F1(x)与F2(x)分别为随机变量X1与X2的分布函数。为使F(x)=aF1
某日,交警甲在乙的小饭馆吃午餐,付给乙餐费100元。当天下午,乙驾车到超市购物时
最新回复
(
0
)