首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
A、The life cycle of trees. B、The number of trees. C、The intensity of solar burning. D、The quality of air. C细节辨认题。短文中指出he found c
A、The life cycle of trees. B、The number of trees. C、The intensity of solar burning. D、The quality of air. C细节辨认题。短文中指出he found c
admin
2014-11-27
52
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://kaotiyun.com/show/yYv7777K
0
大学英语四级
相关试题推荐
Humansaresocialanimals,andmostofustreasureourrelationshipswithfamilyandfriends.An【B1】_____lineofresearchsugges
FrequentbusinesstravelerJoyceGioiaforgotmorethan$20000worthofjewelryinherhotelroominItalylastyear.Luckily
FrequentbusinesstravelerJoyceGioiaforgotmorethan$20000worthofjewelryinherhotelroominItalylastyear.Luckily
Thedictionarysaysatrendisakindofmovementordirection.Peoplearoundtheworldusedtheir【B1】______tobuygoods,commu
A、ReadingsomethingabouttheGreatWall.B、Takingavacation.C、VisitingtheSummerPalace.D、TeachingEnglish.D细节辨认题。女士问男士的暑假
FreeSchoolMealsMillionsofAmericanschoolchildrenarereceivingfreeorlow-costmealsforthefirsttimeastheirparen
A、Inalibrary.B、Inabookstore.C、Inabookcompany.D、Inabookingoffice.A女士说每个人最多只可以借三本书,而男士拿了四本,男士说他将放回去一本,并表示一定会按时归还其他三
A、He’sbusywithreading.B、He’sbehindhisschedule.C、Heiswritingabook.D、Heisfinancedbyhisparents.A
Theproportionofadultswhosaidtheywentona10-minutewalkatleastonceaweekincreasedto62percentin2010,from56pe
A、Newly-launchedproducts.B、Drugusers.C、Surveyresults.D、Publicfigures.C女士问男士昨天进行的关于毒品使用与健康的调查的数据是否可靠,男士作出了回答,可知C为答案。
随机试题
活跃期宫口扩张异常:第二产程胎头下降异常:
女性,40岁,因突起腹中部疼痛伴血便3天入院。腹痛为阵发性,伴恶心、呕吐。呕吐和为胃内容物,起病后曾解黏液血便3次。患者于1个月前腹痛开始反复发作,伴解黏液血便,腹痛发作时,自感有“气块”在腹内串动。查体:消瘦、贫血貌,腹稍胀,全腹软,无局限性压痛及肌紧张
某事业单位以银行存款购入3年期国债,支付投资价款100万元,则下列会计处理正确的有()。
下边这个“金字塔”中每格数字都是该格所对应的下面两格数字之和,如,16是4和12之和。则问号代表的数字是()。
小张通过对20余位专家的访谈得出了“幼儿园教师在职培训”的误区、问题、对策建议,并将其总结为五点。他从专家访谈中得出五条建议的方法是
解决“三农”问题的根本途径是()
J2SDK的基本命令中用于Java类文件归档的是【】。
What’stheproblem?
Whentravelerslackanawarenessof【51】timeisregulatedinaforeigncountry,theycanexpecttofeelsomewhatdisoriented.S
Motherinsistedthat______.
最新回复
(
0
)