首页
登录
职称英语
[originaltext] You can tell the age of a tree by counting its rings but thes
[originaltext] You can tell the age of a tree by counting its rings but thes
游客
2023-07-04
21
管理
问题
You can tell the age of a tree by counting its rings but these records of trees’ life really say a lot more. Scientists are using tree rings to learn what’s being happening on the sun’s surface for the last ten thousand years. Each ring represents a year of growth. As the tree grows, it adds a layer to its trunk taking up chemical elements from the air. By looking up the elements in the rings for a given year, scientists can tell what elements were in the air that year. Doctors Stevenson is analyzing one element — carbon-14 in ring 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’s 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 20 to 22 are based on the passage you have just heard.
20. What do the scientists want to learn by using tree rings according to the passage?
21. What affects the amount of carbon-14 on earth?
22. What do we learn from the passage about the solar wind activity?
选项
A、To learn the chemical elements in the Ice Age for the last ten thousand years.
B、To learn the pattern of solar wind activity for the last ten thousand years.
C、To learn the composition of different trees for the last ten thousand years.
D、To learn what’s being happening on the sun’s surface for the last ten thousand years.
答案
D
解析
转载请注明原文地址:https://www.tihaiku.com/zcyy/2808747.html
相关试题推荐
[originaltext]WhenJustinBassettinterviewedforanewjob,heexpectedth
[originaltext]WhenJustinBassettinterviewedforanewjob,heexpectedth
[originaltext]WhenJustinBassettinterviewedforanewjob,heexpectedth
[originaltext]"TheSanFranciscoBayAreaistheplaypenofcounterculture,
[originaltext]"TheSanFranciscoBayAreaistheplaypenofcounterculture,
[originaltext]W:Youdon’tlooktoowell.Maybeyoushouldtakethedayofffro
[originaltext]W:Youdon’tlooktoowell.Maybeyoushouldtakethedayofffro
[originaltext]W:Youlookbettertoday.Howdidyourtestgo?M:Muchbetterth
[originaltext]M:StevenHawkingwarnsthathumanswillhavetomovetootherpl
[originaltext]M:StevenHawkingwarnsthathumanswillhavetomovetootherpl
随机试题
Overhalftheworld’speoplenowliveincities.Thelatest"GlobalReporto
Themomentumisbuildingaheadofnextmonth’sG8summitinScotlandwheret
ExaminationonvirusfromtheVietnamesewomanimpliedthat______.[br]The23-
患者,男,62岁,1年来进行性吞咽困难,日渐加重。胃镜检查,食管中段可见一溃疡型
对鲁迅早期思想发生重要影响的是()A.阶级论 B.社会主义 C.进化论 D
指示对乙肝病毒感染有保护作用的指标为()。A.抗HBs B.HBsAg
下面关于桥梁墩台施工的说法,正确的是()。A.简易活动脚手架适用于25m以上的
在SDH微波中继通信系统中,没有上、下话路功能的站是()。A、端站 B、枢纽站
2013年1~10月我国货物运输总量最大的领域是:A.公路 B.民航 C
男性,62岁。近3个月来逐渐出现上腹不适,进食后饱胀、嗳气,纤维胃镜发现大弯侧胃
最新回复
(
0
)