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 polluti
It didn’t happen overnight The problem of polluted air has been festering for centuries. Suddenly the problem of air polluti
admin
2013-01-28
66
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 envimnmental 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 partion of the year and are replaced the following year, air pollution injury to hardwoods may not be so severe.
Air pollution causes the most damage to _____.
选项
A、hardwoods
B、conifers
C、fruit trees
D、fluorides
答案
B
解析
文章指出,空气污染对树木有影响,针叶林往往会死掉,但对阔叶林的损害就不那么严重。第五 段To conifers….and other environmental stresses.Death often follows.第六段air pollution injuryto hardwoods may not be so severe.
转载请注明原文地址:https://kaotiyun.com/show/R81O777K
0
考博英语
相关试题推荐
Thereisnoquestionthattheoldstyleofairpollutioncouldkillpeople.Inoneweekfollowingtheinfamous"peasouper"fogi
Inordertoworkheretheforeignerneedsaworkpermit,whichmustbe【21】forbyhisprospectiveemployer.Theproblemhereist
The______friendwasexposedintheendtobehiddenrivalwhohadbeenplottingagainstthecompany’smarketinginHongKong.
Don’tcallhimjustacollegeprofessor.Internetentrepreneur,TVpersonality,advisortopresidents,andfriendtotherichan
Thecomponentofthehealthypersonalitythatisthefirsttodevelopisthesenseoftrust.Aswithotherpersonalitycomponent
Whatismeant【51】theword"friend"?Thedictionary【52】itas:."oneattachedto【53】byaffectionoresteem".Americansuset
Whatismeant【51】theword"friend"?Thedictionary【52】itas:."oneattachedto【53】byaffectionoresteem".Americansuset
EnglishasaworldLanguageEnglishisavictimofitsownsuccess.NewspapersinEnglandhavenoticedthattheincorrectus
WiththeUSeconomyslowingdown,layoffsareeverywhere.Noindustryisspared.Ifyouenduphavingtostartover,inaddition
随机试题
我国过去的快速发展靠的是改革开放,未来的发展也必须依靠改革开放,改革开放只有进行时没有完成时。()
男性,43岁,3天前发现黄疸,行腹部B超发现肝内外胆管扩张,胆总管直径2cm,应首选的检查是
全脂奶粉按重量调配,奶粉与水的比例是
"血为气之母"指的是"夺汗者无血"指的是
庆大霉素不良反应SMZ不良反应
A.喉痹B.乳蛾C.白喉D.喉痛E.烂喉痧
建设项目发生某些变化时,企业需按规定进行环境影响评价文件的重新报批,这里所指的变化有()
根据票据法律制度的规定,下列各项中,属于票据基本当事人的有()。
人事争议是指事业单位与工作人员之间因除名、辞退、辞职、离职等解除人事关系以及履行聘用合同发生的争议。()
Theworkforcehasrecentlybeencallingfortheirworkinghourstobereduced.Manycompanieshave_____switchedtoafive-dayw
最新回复
(
0
)