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
2
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] The resistance of some trees to disease can be traced to______.
选项
A、protective foliage
B、thick bark
C、genetic makeup
D、tainted air
答案
C
解析
题目问:树木对疾病的抵抗可以追溯到什么?第四段第四句Scientists believe this difference in response depends on the kind of tree and its genetic makeup.通过这句话可知,科学家们认为,树木对疾病的不同反应取决于树的种类和遗传因素。据此判断,应选择C。
转载请注明原文地址:https://tihaiku.com/zcyy/4028408.html
相关试题推荐
Itdidn’thappenovernight.Theproblemofpollutedairhasbeenfesteringf
Itdidn’thappenovernight.Theproblemofpollutedairhasbeenfesteringf
Itdidn’thappenovernight.Theproblemofpollutedairhasbeenfesteringf
Itdidn’thappenovernight.Theproblemofpollutedairhasbeenfesteringf
Superficialdifferencesbetweenthespecialproblemsandtechniquesofthephysi
AItcanbearguedthattheproblems,evensomethingBasfundamentalastheCever
Theproblemhasbeen______mymindallday.A、preyingonB、gettingatC、takingon
Thetwonewspapersgavedifferent______ofwhathappened.A、versionsB、editionsC、
Wewerediscussingthehousingproblemwhenamiddle-agedmancutinandsaid,"
Theproblemofpollutionaswellasseveralotherissuesisgoingtobediscusse
随机试题
Wheredidtheshootingtakeplace?[br][originaltext]Agunmanhaskilleda
Inasocialsituation,eyecontactwit
原发性肝癌最理想的肿瘤标记物是A.CA125 B.CA199 C.CEA
“防微杜渐”体现的哲学道理是()A.对立统一规律的原理 B.质量互变规律的
以下事项中,构成同一控制下企业合并的有()。 Ⅰ.甲公司发行股份购买控股股东
宗地权属状况调查是指调查人员通过现场勘查对宗地的()等基本情况的调查核实。A:土
运行中的油浸式电压互感器应保持()。微正压$;$微负压$;$零压
一住店客人未付房钱即想离开旅馆去车站。旅馆服务员揪住他不让走,并打报警电话。客人
在WAIS-RC的实施中,一般按照()的顺序进行。 (A)先言语测验、后
(2009年真题)依据企业所得税相关规定,下列表述正确的是()。A.境外营业机
最新回复
(
0
)