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
2024-01-26
21
管理
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、The life cycle of trees.
B、The number of trees.
C、The intensity of solar burning.
D、The quality of air.
答案
C
解析
细节辨认题。短文中指出he found carbon-14 levels change with the intensity of solar burning,故地球上碳14的含量受太阳燃烧强度的影响。所以选C。
转载请注明原文地址:https://tihaiku.com/zcyy/3396960.html
相关试题推荐
[originaltext](22)Sometimesyourbiggestweaknesscanbecomeyourbiggeststren
[originaltext](22)Sometimesyourbiggestweaknesscanbecomeyourbiggeststren
[originaltext](22)Sometimesyourbiggestweaknesscanbecomeyourbiggeststren
[originaltext]Allwritersdreamofsuccess.Yetsomewritersturntheirbackon
[originaltext]Allwritersdreamofsuccess.Yetsomewritersturntheirbackon
[originaltext](16)China’simplementationofauniversaltwo-childpolicywill
[originaltext]M:I’mnevergoingtoshopatSunFashionShopagain!W:It’snot
[originaltext]W:What’syourhobby?Youplaybasketball?M:(8)Idon’twantto
[originaltext]Kenyaisthethird-largestteaproducerintheworld.Almostall
[originaltext]Kenyaisthethird-largestteaproducerintheworld.Almostall
随机试题
A—collectiveactionI—psychologicalsupportB—competitoranalysisJ—performanc
新时代教师队伍建设的根本要求是()。A.牢固树立中国特色社会主义理想信念 B
适用于病情较重者出院前评定的方法是A.极量运动试验 B.定量行走试验 C.次
共用题干 TrafficinOurCitiesThevolumeof
新生儿禁用的抗生素是A.四环素类 B.青霉素类 C.大环内酯类 D.复方磺
对气体含量正常且无增长趋势的设备()。(A)比值没有意义(B)不能进行比值
公共配套设施建设费在房地产开发项目投资估算的费用构成中属于( )。A.土地费用
甲与某房产公司签订一购房合同,双方约定:如交房时房价下跌,买方可要求退房或要求卖
“工程临时延期审批表(B4)”应由()签发。A、监理单位技术负责人 B、监理单
下列选项中,属于隧道监控量测必测项目的有( )。A.衬砌前净空变化 B.拱顶
最新回复
(
0
)