首页
登录
职称英语
[originaltext] You can tell the age of a tree by counting its rings. But thes
[originaltext] You can tell the age of a tree by counting its rings. But thes
游客
2024-01-30
61
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 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、It affects the growth of trees.
B、It has been increasing since the Ice Age.
C、It is determined by the chemicals in the air.
D、It follows a certain cycle.
答案
D
解析
事实细节题。根据短文最后一句The scientists concluded that the solar wind activity must follow the same cycle,可知太阳风的活动遵循着一个相同的周期。所以选D。
转载请注明原文地址:https://tihaiku.com/zcyy/3406592.html
相关试题推荐
Howdidtheearlypeopledotheircounting?Atfirst,theydidalltheircou
Howdidtheearlypeopledotheircounting?Atfirst,theydidalltheircou
Howdidtheearlypeopledotheircounting?Atfirst,theydidalltheircou
Howdidtheearlypeopledotheircounting?Atfirst,theydidalltheircou
[originaltext](22)Californiaisinthemidstoftheworstdroughtonrecor
[originaltext](22)Californiaisinthemidstoftheworstdroughtonrecor
[originaltext](22)Californiaisinthemidstoftheworstdroughtonrecor
[originaltext]Considerthefactthatcropsgenerallyproduceseveralhundre
[originaltext]Considerthefactthatcropsgenerallyproduceseveralhundre
[originaltext]Thisletterishandwritten,anditisbyasurvivoroftheTi
随机试题
Pleaseleaveashortnotewithyournameandcontactdetailsandwewillgetbac
Americaneconomistsoncespoofeduniversityeducationastheonlyindustryin
Inpolicework,youcanneverpredictthenextcrimeorproblem.Noworking
1972年,联合国教科文组织向全世界发出了“走向阅读社会”的号召,要求社会成员人人读书,让读书成为人们日常生活中不可或缺的部分。1995年,联合国教科文
SouthAfricaSafariTopFiveNationalParksandGameReserves[A]ASouth
如果市场部存在舞弊行为,以下哪项超越了内部审计师的职责范围?A.告知从事该不正当
6岁女孩,反复发生支气管肺炎,于2岁体检发现胸骨左缘第2肋间有Ⅰ~Ⅲ级收缩期杂音
A.猪苓汤 B.五苓散 C.防己黄芪汤 D.实脾散 E.真武汤小便不利,
患者,女性,30岁,妊娠5个月,尿频、尿急、尿痛伴肉眼血尿3天。体温38.5℃,
(2021年真题)关于路径一一目标理论的说法,正确的是()。A.路径一一目标
最新回复
(
0
)