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、To examine the chemical elements in the Ice Age. B、To look into the pattern of solar wind activity. C、To analyse the compositi
A、To examine the chemical elements in the Ice Age. B、To look into the pattern of solar wind activity. C、To analyse the compositi
admin
2015-03-20
21
问题
You can tell the age of a tree by counting its rings. But these records of a tree’s life really say a lot more.[16]Scientists are using tree rings to learn what’s been happening on the sun’s surface for the last 10,000 years. Each ring represents a year of growth. As the tree grows, it adds its 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 analysing one element, carbon 14 in rings from both living and dead trees. Some of the rings go back almost 10,000 years to the end of the Ice Age.[17]When Stevenson followed the carbon 14 trail back in time he found carbon 14 levels change with the intensity of solar burning.[18]You see the sun has cycles. Sometimes it burns fiercely. At other times, it’s 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. And 10,000 years of tree rings show that the carbon 14 level rises and falls about every 420 years. But scientists concluded that solar wind activity must follow the same cycle.
16. What’s 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 solar wind activity?
选项
A、To examine the chemical elements in the Ice Age.
B、To look into the pattern of solar wind activity.
C、To analyse the composition of different trees.
D、To find out the origin of carbon 14 on Earth.
答案
B
解析
细节题。短文开头明确提到,科学家正在利用树的年轮来研究太阳表面在过去一万年的变化(what’s been happening on the sun’s surface),后面又说,通过研究树的年轮可以了解空气中碳14的含量,进而了解太阳风活动密度(the intensity of solar winds),由此可知科学家研究树的年轮是为了了解太阳风的活动频率,故答案为B)。
转载请注明原文地址:https://jikaoti.com/ti/RT3FFFFM
0
大学英语四级
相关试题推荐
ThefloodofwomenintothejobmarketboostedeconomicgrowthandchangedU.S.societyinmanyways.Manyin-homejobsthatuse
A、GiveJackadifferentoffice.B、Complaintothedepartmenthead.C、Movethesuppliestothestorageroom.D、Trytogetaroom
HowtoUseaLibraryA)You’redrivingyourcarhomefromworkorschool.Andsomethinggoeswrong.Theenginestallsoutatligh
A、Attheairport.B、Inarestaurant.C、Inabookingoffice.D、Atthehotelreception.D女士说她没有找到男士的预订记录,男士解释说秘书称已经给他订好了房间,他在早上上飞机
A、Heissurprisedbyit.B、Hedisagreeswithit.C、Hethinksitistoosoontotell.D、Heisalarmedbyit.B题干问的是讲话者对于“电子音乐将会毁掉
Somedayastrangerwillreadyoure-mailwithoutyourpermissionorscantheWebsitesyou’vevisited.Orperhapssomeonewillca
A、Pamela’sreportisnotfinishedasscheduled.B、Pamelahasahabitofdoingthingsinahurry.C、Pamelaisnotgoodatwriting
A、Heisunluckytofalloffaladder.B、Thingsareasbadashethought.C、Thereisnobigdealtobreakaleg.D、Hisinjuryis
Drinkfromplasticbottlescanraisethebody’slevelsofacontroversial"gender-bending"chemicalbymorethantwothirds,acc
OnOccupyingSeatsinCollege1.大学校园里占座是很普遍的现象2.针对这一行为,人们持不同观点3.我的看法
随机试题
选择样本时应注意()
下列是动脉粥样硬化易患因素的是
新生儿,胎龄35周,出生体重2000g,按新生儿分类应属于()。
患者男性,45岁。肛旁反复破溃流脓水近1年,查体见肛旁截石位10点距肛缘6cm处有一破口,诊断为肛瘘。其内口最可能的部位是()
初产妇,因第二产程延长,行左侧会阴切开+低位产钳助产,娩出4000g一活婴。产后2小时伤口疼痛,肛门坠胀并有便意,大便常规检验正常。体检:贫血貌,血压12/SkPa(90/60mmHg),左会阴稍肿,阴道出血不多。下列哪项诊断可能性最大
根据增值税法律制度的规定,一般纳税人取得的进项税额不得从销项税额中抵扣的有()。
在对H公司2005年度会计报表进行审计时,A注册会计师负责筹资与投资循环的审计。在审计过程中,A注册会计师遇到以下事项,请代为做出正确的专业判断。
当前我国金融深化可选择的正确途径是()。
外商投资旅行社,经审批,可以经营()。
当前中国改革的性质是社会主义经济体制的自我完善。()
最新回复
(
0
)