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
42
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
Theoutputofthisyearincreasedtofivetimesoverlastyear.A、今年产量五次增加,超过去年产量
[originaltext]Withinacontextofrapidtechnologicalchangeandshiftingma
[originaltext]M:Ihaveaspecialguesttoday,Shirley.Shirley,youtrulyhave
[originaltext]Moderator:Hello,ladiesandgentlemen.Itgivesmegreatple
【B1】[br]【B5】A、restoreB、storeC、destroyD、damageA该题考点为动词词义辨析。表达“恢复地球的健康”,而不是破
根据以上材料可以看出,机关工作人员()。 A.职业道德应该有明确的行为规范
下表为CBR试验部分试验数据,请回答以下问题:(5)CBR试验泡水测膨胀量试验时
关于检查商业银行是否建立了完善银行卡操作规程并严格按章执行的内容,说法错误的是(
下列因素除外哪一项均与糖尿病发生有关A.某些药物的使用 B.肥胖 C.遗传
下列纠纷可以申请仲裁的是()。A.建筑工程施工纠纷 B.婚姻纠纷 C.劳动纠
最新回复
(
0
)