首页
登录
职称英语
It didn’t happen overnight. The problem of polluted air has been festering f
It didn’t happen overnight. The problem of polluted air has been festering f
游客
2025-04-06
43
管理
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 mall 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 the 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 environmental factors.
For the most part, air pollutants injure 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, diseases, 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. [br] We can conclude that______.
选项
A、air pollution is easier to control than water pollution
B、the problem of polluted air is a problem overnight
C、the impact of air pollution has been known for centuries
D、research on the effects of air pollution is incomplete
答案
D
解析
题目问:通过文章内容我们可以得出什么结论?第四段第句Scientists have not yet been able to obtain a complere report on the effects of air pollution on trees.通过这句话可知,关于空气污染对树木的影响问题,科学家还没有得到完整的结论。据此判断,应选择D。
转载请注明原文地址:https://tihaiku.com/zcyy/4028411.html
相关试题推荐
Itdidn’thappenovernight.Theproblemofpollutedairhasbeenfesteringf
Itdidn’thappenovernight.Theproblemofpollutedairhasbeenfesteringf
Itdidn’thappenovernight.Theproblemofpollutedairhasbeenfesteringf
Thepolice______toemergenciesinjustafewminuteswhentheaccidenthappened.
Superficialdifferencesbetweenthespecialproblemsandtechniquesofthephysi
Itisnaivetoexpectthatanysocietycanresolveallthesocialproblemsitis
AItcanbearguedthattheproblems,evensomethingBasfundamentalastheCever
Theproblemhasbeen______mymindallday.A、preyingonB、gettingatC、takingon
Archaeologyasaprofessionfacestwomajorproblems.First,itisthepoore
Itisimpossibletosayhowitwilltakeplace,becauseitwillhappen______,an
随机试题
Therichhavetraditionallypassedtheirwealthontotheirchildren.Butan
IcametoAfricawithonepurpose:Iwantedtoseetheworldoutsidethepe
MarkTwain’sinstructionswerequiteclear:hisautobiographywastoremain
ALookThatConveysaMessageTotouranassemblyplant
____________(考虑到所有情况),theplannedtripwillhavetobecalledoff.Allthingsha
在总线设备上使用的手动拨码开关一般分为:()。A.二进制 B.六进制 C.
2012年中秋、国庆黄金周期间,全国纳入监测的119个直报景区点旅游收入比上年同
我国宪法规定的公民劳动权包括()。 A.国家为劳动者创造就业条件 B.国家通
患者,男,28岁,下前牙剧烈肿痛3天就 应急处理后永久性治疗方法是A.干髓
(2020年真题)土工合成材料的优点有()。A.质量轻 B.整体连续性好
最新回复
(
0
)