首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
A、The cutting of diamonds needs to have some changes. B、The environment of making diamonds has changed. C、The composition of roc
A、The cutting of diamonds needs to have some changes. B、The environment of making diamonds has changed. C、The composition of roc
admin
2014-05-30
70
问题
Diamonds are the hardest substance known on Earth and they make sparkling jewelry as well as saw blades that can cut through pretty much anything.
Recently, geologists studying diamonds have identified the ages of thousands of diamonds from Southern Africa, where the mineral is most abundant. Their research found that there were only three times in Earth’s history when diamonds were made and that Earth no longer makes diamonds like it used to. "Something was different then. Perhaps the planet was hotter on the inside, or the composition of the rocks was subtly different. Whatever it was it has changed now," stated Steve Shirey, of the Carnegie Institution in Washington, D.C., one of the project researchers.
The oldest diamonds were made 3.3 billion years ago when Earth was relatively young. The second time diamonds formed was 2.9 billion years ago. Small bits of rock within those diamonds, called impurities, indicate that they probably formed from rocks laid down in a shallow sea suggesting that the carbon that made the diamonds probably came from the remains of ancient sea life. The youngest diamonds on Earth are 1.2 billion years old although a few smaller diamonds are about 100 million years old.
Some people like diamonds because they are pretty, rare, or expensive but Dr. Steve Shirey has a different perspective. "I think of diamonds," he said, "as being tiny time capsules that encase a little piece of rock protecting it for billions of years and providing us with a unique window on ancient times."
19. What does the speaker tell us about diamonds?
20. What does the speaker want to convey by the remarks of Steve Shirey?
21. According to the speaker, when were the youngest diamonds made?
选项
A、The cutting of diamonds needs to have some changes.
B、The environment of making diamonds has changed.
C、The composition of rocks is the same as it used to.
D、The demand for diamonds has increased recently.
答案
B
解析
Steve Shirey猜测“以前钻石形成时,地球的内部可能很热,岩石的构造可能有些不一样,但是不管怎样,现在一切都已经改变了。”地球温度和岩石构造都属于钻石形成的环境。故B项正确。
转载请注明原文地址:https://kaotiyun.com/show/oi17777K
0
大学英语六级
相关试题推荐
A、ITindustry.B、Educationindustry.C、Medicineindustry.D、Engineeringindustry.A对话中女士问男士要找什么类型的工作,男士回答说,Actually,Iwanttowo
Childrenhavebeensaidtohavebrain-injuredchildsyndrome,hyperactive(极度活跃的)childsyndromeandattention-deficitdisorder(AD
Childrenhavebeensaidtohavebrain-injuredchildsyndrome,hyperactive(极度活跃的)childsyndromeandattention-deficitdisorder(AD
Therearemanyunitsbywhichtomeasuretheimpactofclimatechange:degreesofincreasingtemperature,feetofrisingsealev
A、They’rewillingtotakerisks.B、Theyhavelong-termfinancialplans.C、Theyseldomgooninstinct.D、Theybuyfewstocks.A男士
A、Therearetoomanypeoplelivingthere.B、Thecostoflivingthereisrelativelyhigh.C、Ithasfrequentnaturaldisasters.D、
TheFutureIsAnotherCountryAcoupleofmonthsorsoafterbecomingBritain’sprimeminister,DavidCameronwantedafewt
Inthe1980s,homeschoolingmadeacomebackintheU.S.whenreligiouslyconservativeparentsconvincedstatestoapproveandgi
A、Theman’sconditionnowisnot;suitableforexercise.B、Themanisnotqualifiedforfootballmatch.C、Theman’slegwasinju
随机试题
《黄帝内经》深受诸子百家学术思想的影响,其中有这么一段话:“心者,君主之官也,神明出焉。肺者,相傅之官,治节出焉。肝者,将军之官,谋虑出焉。胆者,中正之官,决断出焉。膻中者,臣使之官,喜乐出焉。”这段论述受到下列哪一学派思想的影响?()
无极调速时的调速平滑度远大于1。()
神经营养药不包括
【2011年第2题】如图3-449所示悬臂结构,其正确的弯矩图和剪力图是:
已知L工作的紧后工作为M和N。M工作的总时差为4天,持续时间6天;N工作的总时差为3天,持续时间4天;L工作的自由时差为3天。则L工作的总时差为()天。
判断设备成新率的使用年限法中的使用年限可与设备的()相互转换。
偶然因素的特点是()。
Mr.Whitehaslostthekeytothedoor______iskeptinthepocket.
曹操恢复和发展农业生产所采取的主要措施是()。
Marshaconfessedthatsheknewnothingofcomputer.
最新回复
(
0
)