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
2023-07-04
33
管理
问题
You can tell the age of a tree by counting its rings but these records of trees’ life really say a lot more. Scientists are using tree rings to learn what’s being 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 up the elements in the rings for a given year, scientists can tell what elements were in the air that year. Doctors Stevenson is analyzing one element — carbon-14 in ring 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’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. 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 20 to 22 are based on the passage you have just heard.
20. What do the scientists want to learn by using tree rings according to the passage?
21. What affects the amount of carbon-14 on earth?
22. What do we learn from the passage about the solar wind activity?
选项
A、The lifecycle of trees.
B、The number of trees.
C、The intensity of solar burning.
D、The quality of air.
答案
C
解析
转载请注明原文地址:https://tihaiku.com/zcyy/2808748.html
相关试题推荐
[originaltext]Anewstudywarnsthatabout30%oftheworld’speoplemayno
[originaltext]Anewstudywarnsthatabout30%oftheworld’speoplemayno
[originaltext]Anewstudywarnsthatabout30%oftheworld’speoplemayno
[originaltext]Whenmyinterestshiftedfromspacetothesea,1neverexpec
[originaltext]Whenmyinterestshiftedfromspacetothesea,1neverexpec
[originaltext]M:Hi,Rose,youaresoabsorbedthatyoudidn’tevenknowIcame
[originaltext]M:Hi,Rose,youaresoabsorbedthatyoudidn’tevenknowIcame
[originaltext]W:Jack,Iheardyouwerelookingforajob.Haveyoufoundoney
[originaltext]W:Caroltoldusonthephonenottoworryabouther.Herleftle
[originaltext]W:Caroltoldusonthephonenottoworryabouther.Herleftle
随机试题
ScottishwriterAdamSmithisoftenconsideredthemostimportanteconom
【B1】[br]【B2】[audioFiles]audio_eufm_j55_007(20082)[/audioFiles]eliminat
影响离子电导率的因素包括温度、杂质、缺陷()
按结构分,二极管的分类包括()。A.点接触型 B.面接触型 C.平面接触型
张某,女性,55岁,血压155/90mmHg,体质指数26.5kg/m2,血清总
一个车间有多名工人.而每个工人只能在一个车间中工作.车间与工人之间的关系是(
共用题干 第三篇TooLatetoRegretItWhenIwas
(2020年真题)吴老师经常通过和学生聊天来了解他们的知识基础和生活经验,再结合
一般资料:某女,35岁,大专文化,汉族,某中学教师,已婚,经济状况良好。 求助
采用机械开挖土方时,基底预留20∽30cm土,由人工挖掘修整。其目的是()。A.
最新回复
(
0
)