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
31
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
Theconceptofinformationsuperhighwayhasbeenaroundformorethanadeca
Researchonanimalintelligencealwaysmakesuswonderjusthowsmarthumans
Theprimarypurposeofthepassageistopropose______[br]Theauthoranticipat
Livinginthenorthernpartofthecountryhasitsproblems,______obtainingfr
Itwasdifficultforhimtobuygoodshoesbecausehehadsuchabig______off
下列关于蒸汽直接通入水中的加热方式的叙述,不正确的是()。A.经技术经济比较
以下关于单元测试的叙述,不正确的是()A.单元测试是指对软件中的最小可测试单元进
基金管理人进行登记备案应遵循的原则是()。 Ⅰ.及时性; Ⅱ.信息报送的准
《变电运维管理规定》:全面巡视:二类变电站每()不少于1次。周$;$1
A.H>a+14h/15 B.H<a+14h/15 C.H>a+15h/14
最新回复
(
0
)