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
A、It affects the growth of trees. B、It has been increasing since the Ice Age. C、It is determined by the chemicals in the air. D、
A、It affects the growth of trees. B、It has been increasing since the Ice Age. C、It is determined by the chemicals in the air. D、
admin
2018-02-08
20
问题
You can tell the age of a tree by counting its rings. But these records of tree’ s life really say a lot more. Scientists are using tree rings to learn what’s been happening on the sun’s surface for the last ten thousand years. Each ring represents a year of growth. As a tree grows, it adds a layer to its trunk taking up chemical elements from the air. By looking up the elements in the rings from the given year, scientists can tell what elements were in the air that year. Dr. Stevenson is analyzing one element—carbon-14 in rings from both living and dead trees. Some of the rings go back almost ten thousand years to the end of the Ice Age. When Stevenson followed the carbon-14 trail back in time, he found carbon-14 levels change with the intensity of solar burning. You see the sun has cycles. Sometimes it burns fiercely and other times it is relatively calm. During the sun’ s violent periods, it throws off charged particles in fast moving strings called solar winds. The particles interfere with the formation of carbon-14 on earth. When there’s more solar wind activity, less carbon-14 is produced. Ten thousand years of tree rings show that the carbon-14 level rises and falls about every 420 years. The scientists concluded that the solar wind activity must follow the same cycle.
Questions 16 to 18 are based on the passage you have just heard.
16. What is the purpose of the scientists in studying tree rings?
17. What affects the amount of carbon-14 on earth?
18. What do we learn from the passage about the solar wind activity?
选项
A、It affects the growth of trees.
B、It has been increasing since the Ice Age.
C、It is determined by the chemicals in the air.
D、It follows a certain cycle.
答案
D
解析
事实细节题。根据短文最后一句The scientists concluded that the solar wind activity must follow the same cycle,可知太阳风的活动遵循着一个相同的周期。所以选D。
转载请注明原文地址:https://kaotiyun.com/show/W0a7777K
0
大学英语四级
相关试题推荐
A、Hedidnotnoticeit.B、Hedrovetoofasttoreadit.C、Itsays45milesanhour.D、Itisnotclearlyvisible.A根据选项中的notnoti
A、DeputySecretary.B、Foreignminister.C、Countrycommissioner.D、Stategovernor.C短文说她首先做过行政长官,然后当上了德克萨斯州财政部长,故C正确。
Low-carbonFuture:WeCanAffordtoGoGreen[A]Tacklingclimatechangewillcostconsumerstheearth.Thosewhocampaignfora
A、Anassistedsuicideorganization.B、Atravelagency.C、Ahospital.D、Apolicestation.A题目问的是Dignitas是什么。新闻中提到,Dignitas是一个在瑞士的
WhyMoneyDoesn’tBuyHappinessWhatdotheexpertssay?[A]Allinall,itwasprobablyamistaketolookfortheanswertothe
Eatingfruitsandvegetableshasprovedhelpfulinpreventingvariouschronic(慢性的)illnesses.Doesthatmeanthemorethebetter?
长久以来,中国被称为“自行车王国”(kingdomofthebicycle).中国拥有的自行车数量高居世界榜首。然而,随着社会的发展,骑自行车的人有所减少。如今,中国自行车年增长率不超过10%,但高端自行车(high-endbike)年增长率却高达
ArtificialIntelligence(AI)A)Weoftendon’tnoticeit,butartificialintelligence(AT)isallaroundus.Itispresentinco
ArtificialIntelligence(AI)A)Weoftendon’tnoticeit,butartificialintelligence(AT)isallaroundus.Itispresentinco
Accordingtoasurvey,whichwasbasedontheresponsesofover188,000students,today’straditional-agecollegefreshmenare"
随机试题
这个标志是何含义?
评价阻塞性通气功能障碍最主要的指标是
A.Miles手术B.Hartmann手术C.Dixon手术D.拉下式直肠癌切除术距肛门口7~10cm的直肠癌多采用
药店新进一批药品,药师在验货时除进行常规检查外,还应注意有无酸败气味、霉变、结晶析出的药品剂型是
某工程施工到2004年1月,已完工程实际费用为17007万元,已完工程计划费用为1400万元,拟完工程计划费用为1500万元,则该工程此时的进度偏差为()。
某企业资产总额为100万元,当发生下列三笔经济业务后:①向银行借款20万元存入银行:②用银行存款偿还账款5万元;③收回应收账款4万元存入银行,其资产总额为( )。
开放式基金的交易价格取决于()
一个人只要是诚实的,那么他一定就是一个守法公民。以下哪项对此最能构成反驳?()
价值规律发挥作用的表现形式有
AWaysofDeparturefromImmatureandSimplisticImpressionsBCommentonFirstImpressionCIllustrationofFirstImpress
最新回复
(
0
)