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
2015-04-24
45
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 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
细节事实题。根据题干关键词trees定位到原文第四段。本段第四句中的genetic makeup与选项C对应。故答案为C。
转载请注明原文地址:https://kaotiyun.com/show/78LO777K
0
考博英语
相关试题推荐
Cultureshockmightbecalledan【1】diseaseofpeoplewhohavebeensuddenly【2】abroad.Likemostailments,ithasitsown【3】andc
Cultureshockmightbecalledan【1】diseaseofpeoplewhohavebeensuddenly【2】abroad.Likemostailments,ithasitsown【3】andc
Recentlyscientistshavebeen【1】andperfectingothersourcesofenergy:nuclearoratomicpower,solar(sun)power,andsynthetic(
Recentlyscientistshavebeen【1】andperfectingothersourcesofenergy:nuclearoratomicpower,solar(sun)power,andsynthetic(
Recentlyscientistshavebeen【1】andperfectingothersourcesofenergy:nuclearoratomicpower,solar(sun)power,andsynthetic(
IhaveneverseenMrs.Clarkbefore,butIknowfromhermedicalchartandthereportIreceivedfromtheprecedingshiftthatt
Engineeringstudentsaresupposedtobeexamplesofpracticalityandrationality,butwhenitcomestomycollegeeducationIam
Linguistshaveunderstoodfordecadesthatlanguageandthoughtarecloselyrelated.Humansconstructrealityusingthoughtand
Ifoundthesubjectverydifficult,andatonetimethoughtIshouldhavetogiveitup,butyoudirectionsaresoclearand____
Researchershavestudiedthepoorasindividuals,asfamiliesandhouseholds,asmembersofpoorcommunities,neighborhoodsand
随机试题
下列关于股东行使表决权的说法正确的是()
在筹资与投资循环中,被审计单位在会计记录、授权和执行等方面明确职责分工,其目的是为实现哪项认定()
胃癌的癌前期状态不包括
某技术方案现金流量表的数据如下表所示,该技术方案静态投资回收期为()年。
长运股份有限公司(本题下称长运公司)为增值税一般纳税人,适用的增值税税率为17%;不考虑增值税以外的其他相关税费。长运公司2009年至2012年与投资有关的资料如下:(1)2009年11月2日,长运公司与华为公司签订股权购买协议,购买华为公司40G的股权
义务消防队伍建立后应定期对义务消防人员进行消防实操训练及消防常识的培训,每()还应进行一到两次的消防实战演习。
幼儿有吮吸手指的不良习惯.教师应()。
深化文化体制改革,推动社会主义文化大发展大繁荣的根本任务是:
孔子文化节不仅是一场文化盛宴,更是对“郁郁乎文哉”的文明盛象的具体呈现。从最初的“孔子诞辰故里游”到今天的“孔子文化节”,变化的不只是名称,更是不断饱满的文化________和不断厚植的文化________。依次填入画横线部分最恰当的一项是()。
Overthelast25years,Britishsocietyhaschangedagreatdeal--oratleastmanypartsofithave.Insomeways,however,very
最新回复
(
0
)