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
2025-04-09
23
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 re-spond 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 pol-lutant,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 envimn-mental 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. [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“Scientists believe this difference in responsedepends on the kind of tree and its genetic makeup,”通过这句话可知,科学家认为,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:http://tihaiku.com/zcyy/4033437.html
相关试题推荐
Itisnaivetoexpectthatanysocietycanresolveallthesocialproblemsitis
Theincreaseinstudentnumbers____manyproblemsfortheuniversities.A、forcesB
Haveyoueverreceived_____ofwhathashappenedtoher?A、thewordB、wordsC、word
Itdidn’thappenovernight.Theproblemofpollutedairhasbeenfesteringf
Itdidn’thappenovernight.Theproblemofpollutedairhasbeenfesteringf
Itdidn’thappenovernight.Theproblemofpollutedairhasbeenfesteringf
Itdidn’thappenovernight.Theproblemofpollutedairhasbeenfesteringf
Growingeconomicproblemswere____byadeclineinoiloutput.A、highlightedB、foc
Violenceisjustoneofthemanyproblems____incitylife.A、abundantB、inherent
SDSmembersbelievedthatseriousproblemsplaguedthecountry,suchaseconomic
随机试题
[originaltext]Interviewer(M)MilityHopson(W)Now,listentoPartOneoftheint
双组分路面标线涂料干膜厚度一般控制在0.5~2.5mm之间。()
能力验证活动的常用类型包括()等。A、定量计划 B、定性计划 C、顺序计划
企业自由现金流量折现模型是利用企业预期的实体现金流经必要报酬率折现得出的现值估算
2018年全国互联网业务收入9562亿元,比上年增长21.0%。其中,广东、上海
公司的剩余资产在分配给股东之前,应先支付的有()。 Ⅰ.清算费用 Ⅱ.职工工
Thechangeinthatvillagewasmiraculou
以下措施()可作为减少接触电压和跨步电压。接地网的布置应尽量使电位分布均匀;增设
收购要约约定的收购期限不得少于30日并不超过60日。()
属心身疾病的是A.小叶性肺炎 B.精神发育迟滞 C.消化性溃疡 D.肿瘤
最新回复
(
0
)