Leonardo da Vinci was the first man to suggest that growing trees add a new ring in their trunks each year. The 11 in these rings relates to the physical conditions which the tree experiences. Thus, trees grown in a 12 area and time each develop a pattern or configuration of their rings.
This 13 was of little significance until Andrew E. Douglas began to study tree rings in Arizona in 1900. Using a technique called cross dating, he was able to employ tree rings to the study of archaeological sites and date the ruins with 14 . Some were as old as 6700 B. C. ! This study of tree rings is called dendrochronology.
In time the cross dating was 15 by a carbon 14 process. This approach measured the amount of carbon 14 radiating from a piece of wood and 16 to determine the age of that wood. Further use of the carbon 14 technique has shown that the radiation process is more complex and less 17 than had been at first thought.
The most 18 aspect of tree ring research is now called
dendroclimatology. This 19 of the reconstruction of climates and climatic cycles and events from the evidence found in the tree rings. From this it is hoped that a 20 of drought cycles can be determined in the American Southwest. Such information will be of great help in determining the life and ecology of that region of the United States.
A. thus B. model C. variation D. concept
E. accuracy F. exciting G. consists H. given
I. proposition J. composes K. further L. pattern
M. supplemented N. reliable O. excellent
II. C 12. H 13. D 14. E 15. M 16. A 17. N 18. F 19. G 20. L
美国制裁六名塔利班和哈卡尼激进分子
体坛英语资讯:Across China: Skiing birthplace proves a dreamland for off-piste skiers
国内英语资讯:China gains say on intl stage in science and technology: official
谋求提高声望,中国推动海上合作研究
新浪微博热搜榜等板块下线整改
国内英语资讯:First volume of Xis book on governance republished
白宫公布移民改革框架
体坛英语资讯:Leon Goretzkas move to Bayern causes consternation among Schalke fans
国内英语资讯:Heavy snow wreaks havoc in east, central China
国内英语资讯:US falls behind China in global leadership approval: survey
一周热词榜(1.20-26)
体坛英语资讯:Barcelona confirm Mascheranos transfer to Hebei China Fortune
中国企业家达沃斯吐金句 马云:如果贸易停止,世界就会停止
体坛英语资讯:Kings Cup quarterfinal return legs promise thrills in Spain
国际英语资讯:Turkeys Erdogan blames U.S. arms still flowing into Kurds in Syria
国际英语资讯:Milos Zeman wins Czech presidential election
一句话总结各国料理:中餐要探问星空?
小测验 — 如何表达“同意”和“不同意”
警报!警报!流感席卷全球,你中招了么?
国内英语资讯:Chinas backwoods open to the Belt and Road
国际英语资讯:Moscow reserves right to respond to new U.S. sanctions: Russian FM
体坛英语资讯:Lebron James becomes seventh player to reach 30,000 career points in NBA
国内英语资讯:Rich Chinese show rising optimism on economy, survey
美文赏析:如果目标太远大,就不要注视它
研究:女性是最难相处的家庭成员
《无问西东》:谨以此篇献给珍贵的你
喀布尔发生汽车炸弹袭击,至少17人死亡
英语美文:不要瞧不起稳定的生活
国内英语资讯:China-ASEAN trade volume hits record high in 2017
体坛英语资讯:Viva China, Eredivisie champs Feyenoord launch nationwide youth training academy
不限 |
英语教案 |
英语课件 |
英语试题 |
不限 |
不限 |
上册 |
下册 |
不限 |