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
47
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://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
Womenarehalfthepopulationbutonly15%ofboardmembersatbigAmerican
Libyahadeverbeenregardedasoneoftheterrorism-supportingcountriesbefore
[originaltext]W:IthoughtIwasspeakingEnglishfairlywell,butpeoplekeep
Forthispart,youareallowed30minutestowriteashortessay.Youshouldsta
《雷和雨》、《潮汐》、《椅子上的传说》、《我们看见了河岸》是哪位舞蹈家的代表作品
温病病人在热入营分时,舌色应为A、红 B、紫 C、青 D、绛 E、淡白
四川眉山有这样一首题词:“一门三父子,都是大文豪。诗赋传千古,峨眉共比高。”其中
多发性骨髓瘤是一种A.免疫增殖病 B.原发性免疫缺陷病 C.器官特异性自身免
基础设施部门具有的特点包括()。A.投资额大 B.建设周期短 C
质量改进的步骤分为:选择课题,掌握现状,()和总结。 A.分析问题原因B.
最新回复
(
0
)