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
Trillions of incredibly tiny diamonds, possibly formed by a dying star before the solar system was born 4.5 billion years ago, h
Trillions of incredibly tiny diamonds, possibly formed by a dying star before the solar system was born 4.5 billion years ago, h
admin
2010-04-24
57
问题
Trillions of incredibly tiny diamonds, possibly formed by a dying star before the solar system was born 4.5 billion years ago, have been found by researchers 【C1】______ four meteorites.
The powder-like diamonds could be among the oldest things in the 【C2】______ , said Roy Lewis, senior research associate at the University of Chicago.
The diamonds may 【C3】______ clues about the chemistry of stars, and if scientists can determine how they formed, that could suggest better ways of manufacturing tiny diamonds for 【C4】______ purposes, he said.
"It’s quite possible that nature is doing it more 【C5】______ than we’ve been doing it," he said. "So maybe we’ve got something to learn."
The new find is 【C6】______ , said John Wood, staff scientist at the Harvard-Smithsonian Centre for Astrophysics. Although diamonds have been found before in meteorites, they were formed relatively recently 【C7】______ the shock of impact, he said in a telephone interview.
But Wood said the new report made him "quite sure" the newly found diamonds are older than the sun.
Lewis said researchers never expected to find diamonds when they started 【C8】______ a stone-like meteorite that had plunged into Mexican cornfield in 1969.
They were studying an unusual carbon dust in the meteorite, and to purify the sample they went though several steps to dissolve other materials. They expected the sample to remain black through the purification, but to their surprise in the final step it turned 【C9】______ .
Lewis said they believed the final stage had dissolved the carbon they wanted to study. But tests showed that the white residue was in fact made of carbon. Other tests found that it contained an unusual combination of forms of the gas xenon, 【C10】______ that it came from outside the solar system.
Still another battery of tests 【C11】______ the residue as diamond dust, so fine that a row of 20,000 grains would extend about the 【C12】______ of a human hair.
The researchers also found diamonds in three other meteorites, Lewis said. Tests showed all four meteorites were as old as the solar system, and that the embedded diamonds did not form within the meteorite 【C13】______ of collisions.
So the diamonds must have 【C14】______ somewhere else before the meteorites formed, making them as old or older than the solar system.
The diamonds may have formed in the upper atmosphere of a star in the late "red giant" stage, where the temperature and abundance of hydrogen could 【C15】______ diamonds to form as carbon gas condenses.
【C11】
选项
A、concluding
B、detected
C、located
D、identified
答案
D
解析
identified“确认”,此处指“另外有一组实验确认残渣为金刚石灰”。
转载请注明原文地址:https://kaotiyun.com/show/eJ2K777K
0
专业英语四级
相关试题推荐
Mountingevidencehasledastronomerstojustanimprobableconclusion;Atleast90percentandpossibly99percentofallmatte
WhichisNOTnecessaryatafuneralinWesterncountries,accordingtothepassage?
NootherholidaythatistodaywidelyobservedinNorthAmericabassuchalongandcurioushistoryasThanksgiving.Throug
Nomatterhowfrequently______,theworksofBeethovenalwaysattractlargeaudiences.
Jimmyearnshislivingby______worksofartinthemuseum.
Withtheimprovementofourlivingstandard,peoplearemoreconcernedwiththeirhealththanever.Sonowyoucanseemanypeop
IntenseConcentrationAswithanysubject,peoplelearnfasterwhenconcentrationishighandwe’reactivelyinterestedin
Massivechangesinalloftheworld’sdeeply______sportinghabitsareunderway.
Nancybecameataxidriverbecause
Four【C1】______badhabits【C2】______smoking,drinkingtoomuch,【C3】______andpoordiet—can【C4】______youby12years,soberingne
随机试题
患者,男性,25岁。左上腹撞击伤2小时,左上腹疼痛伴轻度恶心,未呕吐,伴心悸、出冷汗。查体:血压82/48mmHg,肠鸣音6次/分,移动性浊音(+),左上腹轻度压痛,反跳痛(±),局限性腹肌紧张。该患者腹穿后可抽出不凝血,最可能的原因是
小儿腹泻发病率高的年龄组是
施工项目管理规划大纲的内容包括( )等。
()具有对饭店设备进行周期性修理的特点,故又称计划维修。
《宪法》规定,国家企事业单位工作人员就职时应当依照法律规定公开进行宪法宣誓。()
能使我国宪法修改生效的表决,通过人数为()。
12,14,20,38,()
党的十八届三中全会通过的《中共中央关于全面深化改革若干重大问题的决定》指出,全面沥化改革的总目标是()
窗体上有一个名称为Command1的命令按钮,其单击事件过程如下:PrivateSubCommand1_Click()DimxAsInteger,yAsIntegerStaticzAsIntegerx
A、Comfortable,withaviewofthemountain.B、Comfortable,withaviewofthesea.C、Verylarge,withfreemeals.D、Verylarge,
最新回复
(
0
)