首页
登录
职称英语
[originaltext] Diamonds are the hardest substance known on Earth and they ma
[originaltext] Diamonds are the hardest substance known on Earth and they ma
游客
2023-09-13
13
管理
问题
Diamonds are the hardest substance known on Earth and they make sparkling jewelry as well as sawblades that can cut through pretty much anything. They form deep within the Earth’s mantle layer ( about 200 km deep ) when atoms of the element carbon arrange themselves into a lattice under huge amounts of pressure from the load of rocks above.
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 the 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. The youngest diamonds on Earth are 1.2 billion years old although a few smaller diamonds are about 100 million years old. 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.
Some people like diamonds because they are pretty, rare, or expensive but Dr. Steve Shiley 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."
选项
A、4.2 billion years ago.
B、3.3 billion years ago.
C、2.9 billion years ago.
D、1.2 billion years ago.
答案
B
解析
听到原文的"The oldest diamonds were made 3.3 billion years ago" 这句话就可以解答。
转载请注明原文地址:https://tihaiku.com/zcyy/3011083.html
相关试题推荐
[originaltext]Educationissoimportantinthewholeworld.Everycountryta
[originaltext]Educationissoimportantinthewholeworld.Everycountryta
[originaltext]Educationissoimportantinthewholeworld.Everycountryta
[originaltext]M:Hi,Diana.MindifIsitdown?W:Notatall,Jack.Howhavey
[originaltext]M:Hi,Diana.MindifIsitdown?W:Notatall,Jack.Howhavey
[originaltext]M:Hi,Diana.MindifIsitdown?W:Notatall,Jack.Howhavey
[originaltext]W:IfIunderstandyoucorrectly,Mr.Savage,youweredrivingwe
[originaltext]W:IfIunderstandyoucorrectly,Mr.Savage,youweredrivingwe
[originaltext]Why,youmaywonder,shouldspidersbeourfriends?Becauseth
[originaltext]Why,youmaywonder,shouldspidersbeourfriends?Becauseth
随机试题
Whichkindoftransportisthemansuggestingthatthewomantakes?[br][origi
[originaltext]Harrison’sDepartmentStoreinvitesyoutoawinterclearance
A.转移癌 B.多发性骨髓瘤 C.肝癌 D.非霍奇金淋巴瘤
A.昆仑 B.申脉 C.太溪 D.照海 E.公孙内踝高点正下缘凹陷处的腧
厚朴“燥湿消积、行气平喘”功效相关的药理作用不包括的是A.促进消化液分泌 B
对急性胰腺炎诊断有价值的化验检查是()。A.甲胎蛋白增高 B.癌胚抗原增高
下列关于生态系统服务的表述,错误的是( )。A.生态系统服务在人类产生之前就客
目前我国证券市场推出的权证均为债权类权证,其标的资产可以是单只债券或债券组合。
贷款保证的目的是对借款人按约、足额偿还贷款提供保障,因此,银行应特别注意保证的(
银行承兑汇票的承兑银行,应当按照票面金额向出票人收取()的手续费。A:千分之一
最新回复
(
0
)