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
82
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/2847533.html
相关试题推荐
[originaltext]Nowinitssixteenthyear,thisyear’sWomen’sClubtenkilom
[originaltext]Nowinitssixteenthyear,thisyear’sWomen’sClubtenkilom
[originaltext]Nearly400yearsagoayoungmantraveleduptoLondon.They
[originaltext]ABritishstudyofhowdietaffectsthehealthofnewmothers
[originaltext]M:Say,Lisa,whatshowareyouwatching?W:AnoldJapanesefilm
[originaltext]M:Say,Lisa,whatshowareyouwatching?W:AnoldJapanesefilm
[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
Manypeople--especiallythebaby-boomersbornbetween1946and1964,who
Snow-makersSkiingisbigbusinessnowadays.Butw
WhydoesthecorrespondentsaythatMilosevic’sfirstappearanceisdramatic?[b
设f(x)在[0,4]上连续,且,则f(2)=( )。A.1/4 B.1/3
营业利润是指企业在交纳所得税后可供所有者支配的利润,它等于利润总额减去所得税费用
公安专业工作的危险性体现在( )A.采取强制的、暴力的手段制伏正在实施暴力犯罪
患者,男,36岁。右下颌无痛性肿胀逐渐加重8个月,无疼痛及麻木感。检查:面部不对
监理人首先应争取通过与发包人和承包人协商达成索赔处理的一致意见,如果分歧较大,再
女性,58岁。反复咳嗽、咳痰、喘息32年,加重3天。査体:桶状胸,双肺满布哮鸣音
承包商就已完工,经检验合格的工程提出支付申请,监理工程师复核后,业主批准支付申请
最新回复
(
0
)