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
The atmosphere that originally surrounded Earth was probably much different from the air we breathe today. Earth’s first atmosph
The atmosphere that originally surrounded Earth was probably much different from the air we breathe today. Earth’s first atmosph
admin
2018-06-06
78
问题
The atmosphere that originally surrounded Earth was probably much different from the air we breathe today. Earth’s first atmosphere(some 4.6 billion years ago)was most likely hydrogen and helium—the two most abundant gasses found in the universe—as well as hydrogen compounds, such as methane and ammonia, Most scientists feel that this early atmosphere escaped into space from the Earth’s hot surface.
A second, more dense atmosphere, however, gradually enveloped Earth as gasses from molten rocks within its hot interior escaped through volcanoes and steam vents. We assume that volcanoes spewed out the same gasses then as they do today: mostly water vapor(about 80 percent), carbon dioxide(about 10 percent), and up to a few 10 percent nitrogen. These same gasses probably created Earth’s second atmosphere.
As millions of years passed, the constant outpouring of gasses from the hot interior—known as outgassing— provided a rich supply of water vapor, which formed into clouds. Rain fell upon Earth for many thousands or years, forming the rivers, lakes, and oceans of the world. During this time, large amounts of carbon dioxide were dissolved in the oceans. Through chemical and biological processes, much of the carbon dioxide became locked up in carbon sedimentary rocks, such as limestone. With much of the water vapor already condensed into water and the concentration of carbon dioxide dwindling, the atmosphere gradually became rich nitrogen.
It appears that oxygen, the second most abundant gas in today’s atmosphere, probably began an extremely slow increase in concentration as energetic rays from the sun split water vapor into hydrogen and oxygen during a process called photodissociation. The hydrogen, being lighter, probably rose and escaped into space, while the oxygen remained in the atmosphere.
This slow increase in oxygen may have provided enough of this gas for primitive plants to evolve, perhaps two to three billion years ago. Or the plants may have evolved in an almost oxygen-free(anaerobic)environment. At any rate, plant growth greatly enriched our atmosphere with oxygen. The reason for this enrichment is that plants, in the presence of sunlight, process carbon dioxide and water to produce oxygen.
The passage suggests that oxygen remained in the atmosphere because______.
选项
A、it was caused by outgassing
B、it was heavier than hydrogen
C、hydrogen became trapped in limestone
D、rays from the sun created equal amounts of hydrogen and oxygen
答案
B
解析
转载请注明原文地址:https://kaotiyun.com/show/nLSO777K
本试题收录于:
NAETI中级口译笔试题库外语翻译证书(NAETI)分类
0
NAETI中级口译笔试
外语翻译证书(NAETI)
相关试题推荐
Ihearthatheknowsfourlanguages,suchasChinese,French,GermanandJapanese.
Although"namingrights"haveproliferatedinAmericanhighereducationforthepastseveraldecades,thephenomenonhasrecentl
Inthepopularmind,theInternetistherealizationoftheglobalvillage,wheretheflowofinformationandideasisunimpeded
Severalinternationaleventsintheearly1990sseemlikelyto________oratleastweakenthetrendsthatemergedinthe1980s.
Themorepeopleyouknow,thelessyouhavetimetoseethembutyoucanalwaysreachthemontheInternet.
各位团长,各位同事:我谨在此宣布,第二轮北京六方会谈现在开幕。作为东道主,我们热烈欢迎各方代表团的再次到来。//半年前,也是在这间大厅里,我们成功启动了六方会谈进程,确立了和平解决核问题的方向。半年来,各方之间开展了不间断的对
A、Solarenergy.B、Fossilfuels.C、Newnuclearplants.D、Nonuclearplants.C掌握判断文中观点态度的词语是解答本题的关键,如正确理解第二段“argues…foropeningne
Intheatmosphere,carbondioxideactsratherlikeaone-waymirror—theglassintheroofofagreenhousewhichallowsthesun’s
A、HegenerallycampedaroundwhiletravelinginSpain.B、HeusedtoworkhardinaseasidehotelinSpain.C、Hefounditdifficu
随机试题
商业银行内部风险管理人员根据银行所承担的风险计算出来的、银行需要保有的最低资本量被称为()
某发电厂拟采用悬挂高度为29m的两根平行避雷线和一根高度是29m的独立避雷针联合作为高度为16m设施的防雷保护。已知两根平行避雷线间距离为24m,长度为46m;避雷针与最近一根避雷线两端的距离均是46m。现按有关公式计算、校验此方案的可行性(被保护设施
信息管理部门的主要任务包括()。
下列各项中,属于会计法律的是()。
根据《发票管理办法》,()统一负责全国发票管理工作。
根据《中华人民共和国海关法》规定的设关原则,如果海关监督管理需要,国家可以在现有的行政区划之外安排海关的直接隶属关系。()
欧洲美元,是指一切存放于欧洲的美元存款。()
乙公司以人民币为记账本位币,对外币交易采用交易日0万美元,当日银行的美元买人价为1美元=6.50元人民币,中间价为1美元=6.60元人民币,卖出价为1美元=6.70元人民币。要求:根据上述资料,不考虑其他因素,回答以下问题。将人民币兑换成外币时所产生
设X1,X2,…,Xn是取自总体X的简单随机样本,记E(X)=μ,D(X)=σ2,,则()
Americanshavelongpridedthemselvesasbeingpartofanoptimisticsociety.ButanewresearchdescribesAmericansaspessimis
最新回复
(
0
)