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
2024-02-01
64
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、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:http://tihaiku.com/zcyy/3411289.html
相关试题推荐
[originaltext](22)Californiaisinthemidstoftheworstdroughtonrecor
[originaltext]Considerthefactthatcropsgenerallyproduceseveralhundre
[originaltext]Considerthefactthatcropsgenerallyproduceseveralhundre
[originaltext]Thisletterishandwritten,anditisbyasurvivoroftheTi
[originaltext]Thisletterishandwritten,anditisbyasurvivoroftheTi
[originaltext]M:Hello,Ihaveareservationfortonight.W:Yourname,please.
[originaltext]M:Hello,Ihaveareservationfortonight.W:Yourname,please.
[originaltext]M:Hello,Ihaveareservationfortonight.W:Yourname,please.
[originaltext]W:AreyouallreadyforChristmas?M:Areyoukidding?(8)Ihaven
[originaltext]Anyideawhattheworld’sbestknownEnglishlanguageis?Bef
随机试题
E—mailallowsfamiliesandfriendsaroundtheworldtocommunicateatalowpric
材料入库由接料、验收、入库三个环节组成。()
下列关于一个千步当量正确描述的是()A.一个千步当量等于4km/h中速步行10
有下列情况( )之一的,可以不进行金融企业国有资产评估。A.县级以上人民政府或者
患者男,70岁,糖尿病、阿尔茨海默病入院治疗。今晨进食油条、豆浆时,突然面色发绀
上皮根鞘连续性破坏形成( )。A.福代斯斑 B.牙源性囊肿 C.上皮剩余
浸润型肺结核和慢性纤维空洞型肺结核分型的最主要鉴别依据是A.血沉 B.X线胸片
下列施工计量器具中,属于强制性检定范畴的是()。A.超声波测厚仪 B.声
混凝土结构梁的裂缝控制中,达到“构件虽有拉应力,但不超过混凝土的抗拉强度”是(
A.安全感 B.同情感 C.自豪感 D.责任感 E.依赖感上列各项中,医
最新回复
(
0
)