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、4.2 billion years ago. B、3.3 billion years ago. C、2.9 billion years ago. D、1.2 billion years ago. B听到原文的"The oldest diamonds
A、4.2 billion years ago. B、3.3 billion years ago. C、2.9 billion years ago. D、1.2 billion years ago. B听到原文的"The oldest diamonds
admin
2010-04-30
30
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://kaotiyun.com/show/uUOK777K
0
大学英语六级
相关试题推荐
Theoldestandsimplestmethod,then,ofdescribingdifferencesinpersonalitywasto(36)______peopleaccordingto(37)______
Theoldestandsimplestmethod,then,ofdescribingdifferencesinpersonalitywasto(36)______peopleaccordingto(37)______
Theoldestandsimplestmethod,then,ofdescribingdifferencesinpersonalitywasto(36)______peopleaccordingto(37)______
Theoldestandsimplestmethod,then,ofdescribingdifferencesinpersonalitywasto(36)______peopleaccordingto(37)______
Theoldestandsimplestmethod,then,ofdescribingdifferencesinpersonalitywasto(36)______peopleaccordingto(37)______
A、Fromreligiousorganizations.B、Frompublicsources.C、Fromcorporatesources.D、Fromresearchgrants.BWheredomostAmerican
Fromthefirstsentencewelearnthatresearchers______.TheinvestigationdoneintheIHDprograms______.
Thereportsaysthatbythemiddleofthecenturyintheworstcase,nofewerthansevenbillionpeoplein60countries__________
随机试题
建设单位对电力建设工程施工安全负全面管理责任。应在()内,将保证安全施工的措施向建设工程所在地国家能源局派出机构备案。
具有生油条件,且能生成一定数量石油的地层称为储油层。()
诊断首先考虑为采取哪种/哪些措施可以使头痛尽快缓解
放大电路如题2—10图所示,设晶体管β=50,RC=1.5kΩ,UBE=0.6V,为使电路在可变电阻RW=0时,晶体管刚好进入饱和状态,电阻R应取何值?()
安装固定型铅酸蓄电池时,电池标志、比重计、温度计应排在电池组()。
某政府安全检查人员李某,在对某施工现场进行检查后,收取了施工方700元检查费,用于补贴安全检查人员的午餐,其行为()。
生产的三个阶段是如何划分的?为什么厂商只会在第二阶段生产?
关于质量改进团队,下列说法正确的是()。
应答性行为和操作性行为有什么不同?
在鹏程公司任销售部总监的王明涛收到了一份销售情况统计表,便指派其助理小刘对其中的数据进行整理和分析。请按下列要求帮助小刘完成数据的整理和分析工作:在“咨询商品编码”与“预购类型”之间插入新列,列标题为“商品单价”,利用公式,将工作表“商品单价”中对应的
最新回复
(
0
)