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
36
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
Weneedtomakesurethatwe______ourresourcesasfullyaspossible.
(1)AgiftedAmericanpsychologisthassaid,"Worryisaspasmoftheemotion;themindcatchesholdofsomethingandwillnotle
Theideaofbuilding"NewTowns"toabsorbgrowthisfrequentlyconsideredacure-allforurbanproblems.Itiserroneouslyassu
Theideaofbuilding"NewTowns"toabsorbgrowthisfrequentlyconsideredacure-allforurbanproblems.Itiserroneouslyassu
Theracialtheoryofcivilizationhasceasedtobescientificallyrespectable.Todayweonlyknowitasasophisticalexcusefor
Sociologistsusethetermpowertorefertothecapacityofpeopleorgroupstocontrolorinfluencetheactionsofothers,whet
AlltherecentnewsonAIDSisbad.ThedeathofRockHudson【1】publicconcernaboutthe【2】almosttothepointofpanic.Nowgene
Radarisusedtoextendthe________ofman’ssensesforobservinghisenvironment,especiallythesenseofvision.
Thatparkcontains______reproductionsofsuchfamoussightsinChinaastheGreatWallandtheSummerPalace.
Ihatetoseetherepulsivesightsincommercialsaboutcoldremedies.
随机试题
宋明理学
ThedirectorAwascriticalBatCthewayweDweredoingthework.
咳声清脆者,多属
男性,60岁,以往有劳力型心绞痛,长期服用硝酸甘油,病情尚稳定,近1个月来胸痛再次发作,位于胸骨下段,且多发生在午睡时或晚间入睡后,服硝酸甘油无效,起床站立后可缓解。以往有胆石症史,但从无发作。一周来患者胸痛,发作在清晨5时,且疼痛时间较长,心电图示
下列关于肺癌的描述不正确的是()
张某因涉嫌贪污罪被人民检察院立案侦查,后被取保候审。张某在取保候审期间严重违反有关规定,人民检察院认为需要变更为逮捕措施。请结合案例,回答下列问题:在取保候审期间,张某应当遵守的规定有()。
控制的基本要求包括()。
防腐蚀涂层采用喷涂法是使用最为广泛的涂装工艺,它的优点是()。
根据《水利水电工程标准施工招标资格预审文件》,资格预审公告应当明确载明的申请人资格要求有()。
基因是控制生物性状的遗传物质的基本结构单位和功能单位。()
最新回复
(
0
)