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
79
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、To find out the origin of carbon- 14 on Earth.
B、To analyze the composition of different trees.
C、To look into the pattern of solar wind activity.
D、To examine the chemical elements in the Ice Age.
答案
C
解析
转载请注明原文地址:https://tihaiku.com/zcyy/2847531.html
相关试题推荐
[originaltext]Nowinitssixteenthyear,thisyear’sWomen’sClubtenkilom
[originaltext]ABritishstudyofhowdietaffectsthehealthofnewmothers
[originaltext]M:Say,Lisa,whatshowareyouwatching?W:AnoldJapanesefilm
[originaltext]M:Say,Lisa,whatshowareyouwatching?W:AnoldJapanesefilm
[originaltext]M:Say,Lisa,whatshowareyouwatching?W:AnoldJapanesefilm
[originaltext]W:Welcome,Mr.Johnson.Takeascat,please.Ourmanagerwillbe
[originaltext]W:Welcome,Mr.Johnson.Takeascat,please.Ourmanagerwillbe
[originaltext]Daughter:Dad,dad.What’sforbreakfast?Dad:[Dadmumblessomet
[originaltext]Daughter:Dad,dad.What’sforbreakfast?Dad:[Dadmumblessomet
[originaltext]Daughter:Dad,dad.What’sforbreakfast?Dad:[Dadmumblessomet
随机试题
[originaltext]1.M:HaveyoueverbeentotheRockyMountains?W:Yes,Ihave.
Searchingforloveisnolongerjustafavoritesubjectforsongs.Ithasal
企业财务管理工作的首要任务是:组织供应资金,为扩大销售服务,保证经营活动的资金需
()是一个国家、一个民族发展中更基本、更深沉、更持久的力量。A.道路自信
有关湿疹不正确的是A.环境变应原可加重病情 B.常迁延不愈 C.经常清洗皮疹
利尿降压药的作用机制不包括A:排钠利尿,减少血容量 B:减少血管壁细胞内Na+
“您多大年纪了”属于()。A.封闭式提问 B.开放式提问 C.探索式提问
有专家撰文指出,影响我国动物福利立法进程的因素是多方面的。其中一个重要的原因就是
我国古代用“金”“石”“丝”“竹”指代不同材质、类别的乐器。下列诗词涉及“竹”的
下列关于焦炉烘炉开工安全措施的说法中,正确的是()。A.点火前应先打开煤气阀
最新回复
(
0
)