首页
登录
职称英语
[originaltext] You can tell the age of a tree by counting its rings. But the
[originaltext] You can tell the age of a tree by counting its rings. But the
游客
2023-07-30
72
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 dements in the rings from the given year, scientists can tell what dements were in the air that year. Dr. Stevenson is analyzing one element—earbon14 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 carbon14 trail back in time, he found carbonn4 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 carbon14 co. Earth. When there’s mom solar rand activity, less carbon14 is produced. Ten thousand years of tree fines show that the carbon 14 level rises and falls about every 420 years. The scientists concluded that the solar wind activity must fellow the same cycle.
选项
A、To examine the chemical elements in the Ice Age.
B、To look into the pattern of solar wind activity.
C、To analyze the composition of different trees.
D、To find out the origin of carbon14 on Earth.
答案
B
解析
转载请注明原文地址:https://www.tihaiku.com/zcyy/2882597.html
相关试题推荐
[originaltext]InAmerica,wherelaborcostsaresohigh."do-it-yourself"i
[originaltext]M:So,Andrea,youaregoinghomefortheholidays?W:Isuream.
[originaltext]M:So,Andrea,youaregoinghomefortheholidays?W:Isuream.
[originaltext]M:TheEnergyMinisterannouncedatapressconferenceyesterday.
[originaltext]M:TheEnergyMinisterannouncedatapressconferenceyesterday.
[originaltext]The"Americandream"isanideathatgrewfromTVprograms,b
[originaltext]The"Americandream"isanideathatgrewfromTVprograms,b
[originaltext]Exerciseisbeneficialtoyourheart.A22-yearstudywascon
[originaltext]Exerciseisbeneficialtoyourheart.A22-yearstudywascon
[originaltext]Exerciseisbeneficialtoyourheart.A22-yearstudywascon
随机试题
我多少次想把这一段经历记录下来,但不是为这段经历感到懊悔,便是为觉察到自己要隐瞒这段经历中的某些事情而感到羞耻,终于搁笔。自己常常是自己的对立面。阳光穿窗而
[img]2019m3x/ct_ehaj_ehareadx_0115_201902[/img]BRIEFDESCRIPTIONOFACCIDENT
WhenMr.Blackretired,hisson______thebusiness.A、tookupB、tookoverC、took
Thegoldenruleyourparentsandteacherstaughtyouwasprettysimple:Dou
It’sdifficulttoimaginetheseaeverrunningoutoffish.It’ssovast,so
C
2014~2018年我国的国内生产总值及其增长速度如图1所示: 图1 国内生产
A基金公司首发某开放式基金,其基金合同规定“本基金认购人数应不少于200人,方可
HIV的主要传播途径是()。A.血液传播 B.母婴传播 C.性传播 D.
与雌激素类药物合用,药物疗效降低的有A.抗凝药 B.三环类抗抑郁药 C.抗高
最新回复
(
0
)