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
4
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] Air pollution causes the most damage to______.
选项
A、hardwoods
B、conifers
C、fruit trees
D、fluorides
答案
B
解析
题目问:空气污染对什么树木的损害最大?第五段To conifers,…and other environmental stresses.Death often follows.第六段…air pollution injury to hardwoods may not be so severe.通过这些话可知,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。据此判断,应选择B。
转载请注明原文地址:https://tihaiku.com/zcyy/4028409.html
相关试题推荐
Itdidn’thappenovernight.Theproblemofpollutedairhasbeenfesteringf
Itdidn’thappenovernight.Theproblemofpollutedairhasbeenfesteringf
Itdidn’thappenovernight.Theproblemofpollutedairhasbeenfesteringf
Itdidn’thappenovernight.Theproblemofpollutedairhasbeenfesteringf
Thetwonewspapersgavedifferent______ofwhathappened.A、versionsB、editionsC、
Archaeologyasaprofessionfacestwomajorproblems.First,itisthepoore
Archaeologyasaprofessionfacestwomajorproblems.First,itisthepoore
Wewerediscussingthehousingproblemwhenamiddle-agedmancutinandsaid,"
Manyriversandlakeshavebeen______byindustrialwaste.A、damagedB、polluted
Inthesearchforsolutiontoseeminglyoverwhelmingproblems,itbecameincreas
随机试题
Vitamins,likeminerals,arechemicals.Thereisabsolutelynotdifferencei
TestingTimesResearchersareworkingonways
[originaltext]M:Hello?W:Hello,Alan.ThisisLucy.I’mintrouble.M:Whath
十九届二中全会强调,2018年即将修改的宪法必须贯彻以下原则()A.坚持党的领
下列有关基坑开挖方式说法中正确的是()。A.分层支撑和开挖的基坑上部可采用小型施
Inwriting,_________willgivestudents
A.ABC时间管理法 B.四象限时间管理法 C.记录统计法 D.拟定时间进
下述儿茶酚胺对心肌的作用,哪一项是错误的A.减少自律细胞4期的If内向离子流
农村集体经济统计的研究对象是农村集体经济现象总体的( )。A.质量特征和数量关
胃容受性舒张的传出途径是A.胰泌素 B.迷走神经 C.交感神经 D.壁内神
最新回复
(
0
)