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
2024-02-19
54
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、It follows a certain cycle.
B、It affects the growth of trees.
C、It has been increasing since the Ice Age.
D、It is determined by the chemicals in the air.
答案
A
解析
转载请注明原文地址:https://tihaiku.com/zcyy/3463797.html
相关试题推荐
[originaltext]Airtravelissuchaneverydayexperiencethesedays.Weare
[originaltext]Airtravelissuchaneverydayexperiencethesedays.Weare
[originaltext]Weoftenpassonlittlebitsofinformationtoourchildren,
[originaltext]Weoftenpassonlittlebitsofinformationtoourchildren,
[originaltext]W:Dr.Thomas?ThisisKeetBradleyfromthedailynews.I’dlike
[originaltext]Inthenextfewdecades,peoplearegoingtotravelverydiff
[originaltext]Manyofusbelievethataperson’smindbecomeslessactivea
[originaltext]M:EnglishLanguageCenter.HowmayIhelpyou?W:Yes.I’mcalli
[originaltext]M:EnglishLanguageCenter.HowmayIhelpyou?W:Yes.I’mcalli
[originaltext]M:EnglishLanguageCenter.HowmayIhelpyou?W:Yes.I’mcalli
随机试题
Peopleoftenfocusonthejobandincomepotentialthatcomeswithacolleg
根据资产评估法的规定,符合设立评估机构的条件的有( )。A.应向工商行政管理部门
泌尿系统常见的恶性肿瘤是A.肾癌 B.肾母细胞瘤 C.肾盂肿瘤 D.膀胱癌
A. B.800 C.640 D.200π
下列哪项不符合原发性甲亢的诊断标准?( )A.基础代谢率20% B.2小时甲
材料1: 今年3月,浙江省台州市政府与该市9个县(市、区)签订了食品安全
(2020年真题)下列关于商业银行理财业务特点的表述,正确的有()。A.理
2月中旬,豆粕现货价格为2760元/吨,我国某饲料厂计划在4月份购进1000吨豆
(2021年真题)某施工企业在经营过程中,同时发行可转换债券和认股权证,该筹资方
治疗急性梗阻性化脓性胆管炎最关键的措施是 A.胆总管切开减压 B.胆囊切开减
最新回复
(
0
)