首页
登录
职称英语
[originaltext] You can tell the age of a tree by counting its tings. But the
[originaltext] You can tell the age of a tree by counting its tings. But the
游客
2023-07-18
19
管理
问题
You can tell the age of a tree by counting its tings. But these records of a tree’s life really say a lot more. Scientists are using tree tings 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 the tree grows, it adds a layer to its trunk, taking up chemical elements from the air. By looking at the elements in the rings from a 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 bums fiercely. At other times it’s relatively calm. During the sun’s violent periods, it throws off charged particles in fast moving streams, called solar winds. The particles interfere with the formation of carbon—14 on earth. When there is more solar wind activity, less carbon—14 is produced. Ten thousand years of tree rings show the carbon—14 level rises and falls about every four hundred and twenty years. The scientists concluded that solar wind activity must follow the same cycle.
选项
A、The quality of air.
B、The number of trees.
C、The lifecycle of trees.
D、The intensity of solar burning.
答案
D
解析
转载请注明原文地址:https://tihaiku.com/zcyy/2847532.html
相关试题推荐
[originaltext]Nowinitssixteenthyear,thisyear’sWomen’sClubtenkilom
[originaltext]Nearly400yearsagoayoungmantraveleduptoLondon.They
[originaltext]Nearly400yearsagoayoungmantraveleduptoLondon.They
[originaltext]ABritishstudyofhowdietaffectsthehealthofnewmothers
[originaltext]ABritishstudyofhowdietaffectsthehealthofnewmothers
[originaltext]M:Say,Lisa,whatshowareyouwatching?W:AnoldJapanesefilm
[originaltext]W:Welcome,Mr.Johnson.Takeascat,please.Ourmanagerwillbe
[originaltext]W:Welcome,Mr.Johnson.Takeascat,please.Ourmanagerwillbe
[originaltext]W:Welcome,Mr.Johnson.Takeascat,please.Ourmanagerwillbe
[originaltext]Daughter:Dad,dad.What’sforbreakfast?Dad:[Dadmumblessomet
随机试题
Fiftyvolunteerswerealphabeticallydividedintotwoequalgroups,GroupA
Howlonghasthemansufferedfromthesymptomshedescribed?[originaltext]M:G
Studentsalwayskeepcandlesintheirrooms______thereisapowercut.A、incas
2012年1~5月电子信息产业新增固定资产同比增长量最多的是()A.电
在南宋词坛上与辛弃疾、吴文英鼎足而三的作家是()A.史达祖 B.姜夔 C.陈
哪项不能体现医疗机构从业人员“优质服务、医患和谐”的行为规范:A.自觉遵守国家法
"气之主"指的是()A.肝 B.心 C.脾 D.肺 E.肾
Thechangeinthatvillagewasmiraculou
质点受弹簧力作用而运动,l0为弹簧自然长度,k为弹簧刚度系数,质点由位置1到位置
按水工建筑物围岩工程地质分类法,已知岩石强度评分为25、岩体完整程度评分为30、
最新回复
(
0
)