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
Narrator Listen to part of a talk in an environmental science class. Now get ready to answer the questions. You may use
Narrator Listen to part of a talk in an environmental science class. Now get ready to answer the questions. You may use
admin
2013-04-25
38
问题
Narrator
Listen to part of a talk in an environmental science class.
Now get ready to answer the questions. You may use your notes to help you answer.
According to the speaker, what might be an air pollutant in the future?
How much can you say about air pollutant? At first let’s have a look at a useful definition of it. A pollutant is a compound added directly or indirectly by humans to the atmosphere, and in such quantities to adversely affect humans, animals, vegetations or materials. On the other hand air pollution has a very flexible definition that allows continuous change. When the first air pollution law was established in England in the 14th century, air pollutants were limited to compounds that could be seen or smelled, which is very different from the list of harmful substances known today. As technology has developed and knowledge of health aspects has increased, the list of air pollutants has lengthened. In the future even water vapor might be thought of as an air pollutant under certain conditions.
Many of the more important air pollutants, such as sulfur oxides, carbon monoxide, and nitrogen oxides are found in nature. Perhaps in your daily life you can’t feel them clearly since they don’t make up a big percentage of the air. Before we have learnt something about the properties of the above substances, let’s have a look at their historical development. As the earth developed, the concentrations of these pollutants were altered by various chemical reactions and become biogeochemical components, and then they 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 those resulting from human activities. However, human production usually occurs in a localized area, such as a city.
In these localized regions, human output may be dominant and may temporarily overload the natural purification scheme of cycles. The result is an increased concentration of human activities. The actual concentration need not be large for a substance to be a pollutant; in fact the concentration 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, often shortened to 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.
选项
A、Sulfur oxides.
B、Carbon monoxide.
C、Nitrogen oxides.
D、Water vapor.
答案
D
解析
本题为细节题。题目问:说话者认为将来什么可能是空气污染物?文章的第一段指出“In the future even water vapor might be thought of as an air pollutant under certain conditions”,也就是说,水蒸气现在并不是大气污染物,将来可能成为污染物。其他几项均为干扰项,因为它们现在已经是污染物了,因此我们可以得出选项D为正确答案。
转载请注明原文地址:https://kaotiyun.com/show/ydyO777K
0
托福(TOEFL)
相关试题推荐
SECTION1Questions1-10Questions1-4AnswerthefollowingquestionsusingNOMORETHANTHREEWORDSAND/ORANUMBERforeachga
Questions26-30Identifywhichspeakerisbeingreferredtoineachstatement.Writethecorrespondingletteronyouranswershe
Theprofessorwantsthestudentstopretendthattheyare______.
Theprofessorwantsthestudentstopretendthattheyare______.
Theprofessorwantsthestudentstopretendthattheyare______.
Theprofessorwantsthestudentstopretendthattheyare______.
Questions21-25AnswerthefollowingquestionsusingNOMORETHANTHREEWORDSforeachanswer.
Qusetions5-10AnswerthefollowingquestionsusingNOMORETHANTHRESSWORDSAND/ORANUMBERforeachanswerNUMBERforeach
Completethesummarybelow.UseNOMORETHANTHREEWORDSforeachanswer.PROJECTMANAGENTLastweek’sdefinitionofpro
随机试题
简述业主大会的职责。
欧洲共同体的第一阶段属于________。
患儿,4岁,1个月来反复阵发性咳嗽、发热,咳脓性痰,体质消瘦,X线拍片见左肺有肺不张。如果怀疑是支气管异物,其临床上应属于
A、病变组织病理检查B、大便潜血检查C、B超和CTD、CEA(血清癌胚抗原测定)E、内镜检查可作为普查的初筛手段
根据所给资料,回答问题。社会性别是一个能够影响公共政策制定中公民参与状况的重要变量,其对公民参与的信息来源、参与动机以及参与频次等方面都有十分重要的影响。下面以湖北、湖南、河南、江西、安徽和山西等六省为个案,从量化层面考察了社会性别对于我国政策制
按照设备工程项目的信息来源分类,可以将设备工程项目信息分为( )。
在下列各类错账中,不需要采用红字更正法进行更正的错账有()。
张敏认为,只要违反了规则并给他人带来了伤害,不论动机如何都是不道德的。根据科尔伯格的道德发展观,其道德认知发展处于()。
Youmaybesurprisedtosee"makingsurechildrenneversuffer"asamistake.Thefollowing【C1】__________mayhelpyouunderstand
下列对生成树协议STP的描述中,错误的是
最新回复
(
0
)