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
2015-01-09
54
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
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 stress-es.Death often follows.”第六段air pollution injury to hardwoods may not be so severe.通过这句话可知,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://kaotiyun.com/show/QdQO777K
0
考博英语
相关试题推荐
TheUnitedNationsdeclaredlastFridaythatSomalia’sfamineisover.Buttheofficialdeclarationmeanslittletothemillions
TheUnitedNationsPopulationFundhaspickedOctober31asthedaytheworldwillbehometo7billionpeople.Forbettera
Writersnowadayswhovaluetheirreputationamongthemoresophisticatedhardlydaretomentionprogresswithoutincludingthew
Allthequestions______aroundwhatshehadbeendoingonthenightoftherobbery.
Themost______exampleofwaterpollutionoccurredin1969,whentheCuyahogaRiverinOhiocaughtfireandhelpedshockAmerica
TheAssociationofUniversityTeachersclaimsthattaxpayers’money,______forbasicresearch,isbeingusedtopropupindustri
PsychologistAlfredAdlersuggestedthattheprimarygoalofthepsyche(精神)wassuperiority.Although【1】hebelievedthatindividu
PsychologistAlfredAdlersuggestedthattheprimarygoalofthepsyche(精神)wassuperiority.Although【1】hebelievedthatindividu
Marywasextremelylucky:whenhergreat-uncledied,she____afortune.
Idecidedtogetintouchwithhim______afterIreceivedhisletter.
随机试题
含浆汁、淀粉或糖分多的药材,其产地加工常用方法是
高渗脱水的表现是
根据我国《宪法》的规定,下列关于公民基本权利的宪法保护的表述,哪一项是正确的?
采用股权式合资的新设项目法人,按《公司法》的规定,全体股东的货币出资金额不得低于公司注册资本的()。
出境的交通工具和人员,必须在最后离开的国境口岸接受检疫。( )
信息技术控制包括()。
张教授:利益并非只是物质利益,应该把信用、声誉、情感甚至某种喜好等都归入利益的范畴。根据这种“利益”的广义理解,如果每一个个体在不损害他人利益的前提下,尽可能满足其自身的利益需求,那么由这些个体组成的社会就是一个良善的社会。根据张教授的观点,可以得出以下哪
Studythefollowingpicturecarefullyandwriteanessayto1)describethepicture,2)deducethepurposeofthepainte
Forthispart,youneedtowriteanessayexpressingyouropiniononwhetherawallmakesiteasierormoredifficulttobeago
A、Thedevelopmentofjazzmusic.B、ThemusiciannamedCharlieParker.C、Thenewstyleofjazzcalledbebop.D、ThedeathofCharl
最新回复
(
0
)