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
A useful definition of an air pollutant is a compound added directly or indirectly by humans to the atmosphere in such quantitie
A useful definition of an air pollutant is a compound added directly or indirectly by humans to the atmosphere in such quantitie
admin
2021-12-15
47
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 die concentration mat 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.
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://kaotiyun.com/show/MPx7777K
0
大学英语六级
相关试题推荐
Apple’sStanceHighlightsaMoreConfrontationalTechIndustry[A]ThebattlebetweenAppleandlawenforcementofficialsoveru
Apple’sStanceHighlightsaMoreConfrontationalTechIndustry[A]ThebattlebetweenAppleandlawenforcementofficialsoveru
Apple’sStanceHighlightsaMoreConfrontationalTechIndustry[A]ThebattlebetweenAppleandlawenforcementofficialsoveru
Whatistheplaceofartinacultureofinattention?RecentvisitorstotheLouvrereportthattouristscannowspendonlyami
A、ScientiststriedtosendaballoontoVenus.B、ScientistsdiscoveredwateronVenus.C、ScientistsfoundVenushadatmosphere.
Inwhat’sprobablythecraziestheadlineI’veeverwritten,I’vereportedthat【C1】______inlivestockprotectionarehappening
Inwhat’sprobablythecraziestheadlineI’veeverwritten,I’vereportedthat【C1】______inlivestockprotectionarehappening
AtthebaseofamountaininTanzania’sGregoryRift,LakeNatronburnsbrightred,surroundedbytheremainsofanimalsthatwe
Theroboticsrevolutionissettobringhumansfacetofacewithanoldfear—man-madecreationsassmartandcapableasweareb
Theroboticsrevolutionissettobringhumansfacetofacewithanoldfear—man-madecreationsassmartandcapableasweareb
随机试题
社会工作者在某社区开展需求调研时发现:该社区的低收入家庭中有劳动意愿和能力的妇女共30名。她们大多从农村嫁到城里,婚后长期在家照顾老人和孩子,身边几乎没有能谈心的朋友。由于没有工作收入,她们的家庭地位较低,一旦发生家庭矛盾,只能忍气吞声。因此,她们希望学一
抽油泵下在油井井筒的()一定深度,依靠抽油杆传递抽油机动力,将原油抽出地面。
患儿,男,5岁。食欲旺盛且有喜食高脂肪和甜食的习惯,现体重超出小儿正常标准的25%,被诊断肥胖症。该患儿的治疗原则
A、 B、 C、 D、 D本题正确答案为D。按列看,第1列中线段的数目为4、0、4,第2列线段的数目为5、4、1,第3列线段的数目为8、3,前两列的规律为4=0+4,5=4+1,故下一个图形线段数目为5,故选
负责接收和保管所管辖范围内应当永久和长期保存的工程档案和有关资料的单位是( )。
钢桩在场地堆放时,堆放高度最多为()层。
机电工程中,接闪器的试验内容有()。
根据下列资料。回答第下列问题。2013年全国社会物流总额197.8万亿元,同比增长9.5%,增幅比上年回落0.3个百分点。分季度看,一季度增长9.4%,上半年增长9.1%,前三季度增长9.5%。其中,工业品物流总额181.5万亿元,同比增长9.7%,增
设有以下语句:structSS{intno;charname[10];}PERSON;则下面叙述中错误的是()
Thefridgeisconsideredanecessity.Ithasbeensosincethe1960swhenpackagedfoodfirstappearedwiththelabel:"storein
最新回复
(
0
)