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
Scientists have long believed one way to stop the Earth’s atmosphere from warming is by planting more trees. The idea is that mo
Scientists have long believed one way to stop the Earth’s atmosphere from warming is by planting more trees. The idea is that mo
admin
2010-01-10
62
问题
Scientists have long believed one way to stop the Earth’s atmosphere from warming is by planting more trees. The idea is that more trees will take in or absorb some of the carbon dioxide in the atmosphere. Carbon dioxide is a gas released by cars, factories and other human activities. The gas traps heat in the Earth’s atmosphere, which warms the planet. However, two new studies have found that trees may not be as helpful in reducing carbon dioxide as had been thought.
The first study was done at Duke University in Durham, North Carolina. Researchers pumped extra carbon dioxide into a test area where pine trees were growing. The trees grew thirty-four percent faster during the first three years. However, in time, the trees slowed to about their normal growth rate. The scientists say this is because trees need other nutrients, such as nitrogen.
In the second study, researchers from Duke and Bowdoin College in Brunswick, Maine examined the soil around trees. They discovered that as the leaves broke down into the soil, all the carbon was not trapped in the soil. Much of it was released into the atmosphere as carbon dioxide.
The findings of the two studies were published last month in Nature magazine. They suggest there is limited value in planting trees to reduce the carbon dioxide pollution in the atmosphere.
Forest planting has been a part of negotiations on a world agreement to reduce greenhouse gases that scientists believe cause global warming. The United States, Canada, Japan and some other industrial countries have supported the idea. But this new research suggests the idea is not as effective as environmental activists had thought. Scientist Ram Oren of Duke University led the study on tree growth. He says that earlier estimates on the ability of forests to absorb carbon dioxide were overly hopeful.
Some scientists not involved in the studies say the research provides some of the first evidence on how trees react to carbon dioxide. Other scientists say the research disputes a belief among some coal and power companies. The companies say that rising levels of carbon dioxide in the atmosphere will not create harmful global warming. Instead, they say it will increase forests and other plants.
The word "it" (Line 7, Para. 6) probably refers to ________.
选项
A、carbon dioxide
B、nitrogen
C、atmosphere
D、coal
答案
A
解析
关键语句:The companies say that rising levels of carbon dioxide in the atmosphere will not create harmful global warming.Instead,they say it will increase forests and other plants.可见应是二氧化碳.其余选项与本段无关。
转载请注明原文地址:https://kaotiyun.com/show/Yc6K777K
0
专业英语四级
相关试题推荐
Thefollowingarticleisaboutthe"parenttrigger"lawsintheUS.Thebasicconceptofthepolicyisthatparentshavetheabi
Mostmajoreducationalsystemsutilizesomesortofstandardizedtestforuniversityadmissions.Theimportanceofthesetestsv
(1)TheChildrenAct1989doesnotassuchrequireparentsorpersonsholdingparentalresponsibilitytoeitherinvolvechildren
(1)TheParis-basedInternationalEnergyAgency(IEA),initsannualforecast,saidanumberoffactors,includingthesoaringcos
(1)Sometimesthebiggestchangesinsocietyarethehardesttospotpreciselybecausetheyarehidinginplainsight.Itcouldw
Thefollowingtwoexcerptsareaboutthenecessitytourgestudentstoreadtheclassics.Fromtheexcerpts,youcanfindthatt
ThefollowingtwoexcerptsareaboutartificialintelligenceorAI,anoldtechnologywithrecentprogress,thankstoDeepLearn
Itisaknownfactthatphysicalactivityimprovesoverallhealth.Notonlydoesitimprovecirculation,increasebloodflowto
Whatwouldbeannouncedconcerningtheelections?
Theelectioncampaigniscarriedout______,withalmosteveryoneinvolvedinonewayoranother.
随机试题
国际企业人力资源计划中,对企业总体的发展方向进行安排的计划属于()
正常人主要造血器官为
制宪者通过对宪法历史资料的解读来解释现行宪法的含义,该解释方法是()。
测量准确度可以____________。
某一中等城市,经对周边县改区后扩大为大城市,根据地价管理的要求需进行基准地价更新评估。现委托一土地评估机构进行评估。基准地价评估期日为2004年1月1日。该机构在评估过程中调查了下述资料。(1)调查的样点中,有一个样点P为临街商业店铺,位于二级地,
以下设计变更属于重大设计变更范畴的是()。
总需求曲线向右下倾斜的原因是()。[2008年真题]
下列有关前后任注册会计师沟通的总体要求的说法中,错误的是()。
按照美国学者古德莱德的观点,课程可以分为五个层面,除理想的课程、正式的课程、领悟的课程之外,还有()。
Iremember______tothezoobymyfatherwhenIwasachild.
最新回复
(
0
)