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
It didn’t happen overnight. The problem of polluted air has been festering for centuries. Suddenly the problem of air pollut
It didn’t happen overnight. The problem of polluted air has been festering for centuries. Suddenly the problem of air pollut
admin
2016-01-30
27
问题
It didn’t happen overnight. The problem of polluted air has been festering for centuries.
Suddenly the problem of air pollution is becoming critical and is erupting right before our eyes. Not only do our eyes burn as they focus through murky air, but when the air clears, we see trees and vegetation dying. We must realize that this destruction can no longer be pinned to some mysterious cause. The one major culprit is air pollution.
Today’s air pollution is an unfortunate by-product of the growth of civilization. Civilized man desires goods that require heavy industrialization and mass production. Machines and factories sometimes pollute and taint the air with substances that are dangerous to man and the environment. These substances include radioactive dust, salt spray, herbicide and pesticide aerosols, liquid droplets of acidic matter, gases, and sometimes soil particles. These materials can act alone to irritate objects and forms of life. More dangerously, they join together to act upon the environment. Only lately have we begun recognizing some of their dangerous consequences.
Scientists have not yet been able to obtain a complete report on the effects of air pollution on trees. They do know, however, that sulfur dioxide, fluorides, and ozone destroy trees and that individual trees respond differently to the numerous particulate and gaseous pollutants. Sometimes trees growing in a single area under attack by pollutants will show symptoms of injury or will die while their neighbors remain healthy. Scientists believe this difference in response depends on the kind of tree and its genetic makeup. Other factors, such as tree’s stage of growth and nearness to the pollution source, the amount of pollutant, and the length of the pollution attack also play a part. In short, whether or not a tree dies as a result of air pollution depends on a combination of host and environment factors.
For the most part, air pollutants injury trees. To conifers, which have year-round needles, air pollution causes early balding. In this event, trees cannot maintain normal food production levels. Undernourished and weakened, they are open to attack by a host of insects, disease, and other environmental stresses. Death often follows.
Air pollution may also cause hardwoods to lose their leaves. Because their leaves are borne only for a portion of the year and are replaced the following year, air pollution injury to hardwoods may not be so severe.
The author attributes today’s air pollution to .
选项
A、the growth of civilization
B、man’s carelessness
C、environmental imbalance
D、some mysterious cause
答案
A
解析
细节事实题。根据题干关键词today’s air pollution定位到原文第三段首句。原句中的the growthof civilization与选项A对应。故答案为A。
转载请注明原文地址:https://kaotiyun.com/show/J2GO777K
0
考博英语
相关试题推荐
Ourcountryhadmadegreateffortstopromotethefamily-planningpolicy,but______thebirthrateisgettinghigherandhigher.(
(中国矿业大学2009年试题)Solvingaproblemcanbebrokenintoseveralsteps.First,theproblemmustbeidentifiedcorrectly.Psychol
(中国矿业大学2009年试题)Solvingaproblemcanbebrokenintoseveralsteps.First,theproblemmustbeidentifiedcorrectly.Psychol
Heretheburdenofhisthoughtisthatthephilosopher,aimingattruth,mustnot______theseductionoftryingtowritebeautifu
BBC’sCasualtyprogrammeonSaturdayeveninggaveviewersavoteastowhichoftwopatientsshouldbenefitfromadonation.But
Ileftfortheofficeearlierthanusualthismorning______trafficjam.
Thenewsystemissimilartotheoldone______thereisstillastrongcentralgovernment.
Researchershavestudiedthepoorasindividuals,asfamiliesandhouseholds,asmembersofpoorcommunities,neighborhoodsand
Eventoday,(through)the(hustleandbustle)ofNevskyProspect,StPetersburg’smainstreet,the(classical)beautyofthecit
Duringthepasttenorfifteenyears,agreatdealofattentionhasbeen【C1】______to"tellingitlikeitis,"or"lettingitallh
随机试题
此病最可能诊断为此病的主要致病菌为
银杏木笔花
必须持有《药品经营许可证》的企业是()
(2008年)图8—29所示电路中,IS1、IS2、US均为已知的恒定直流量,设流过电阻上的电流IR如图所示,则以下说法正确的是()。
对于无效合同的财产后果处理有( )。
根据企业固有资产产权登记管理的有关规定,下列选项中,应当依照规定申请办理国有资产产权登记的有()。
已知∣a∣=1,∣b∣=2。(1)若a∥b,求a·b;(2)若a、b的夹角为60°,求∣a+b∣;(3)若a-b与a垂直,求当k为何值时,(ka-b)⊥(a+2b)。
真理的力量加上道义的力量,才能行之久远。社会主义核心价值观居于人类社会的价值制高点,具有强大的道义力量,是源于其具有()
[*]
信息系统的结构化设计(SD)方法中,一般分为总体设计和详细设计两阶段,其中总体设计主要是要建立()。
最新回复
(
0
)