首页
登录
职称英语
The atmosphere that originally surrounded Earth was probably much different
The atmosphere that originally surrounded Earth was probably much different
游客
2025-01-13
11
管理
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. [br] What is the main idea of the passage?
选项
A、The original atmosphere on Earth was unstable.
B、The atmosphere on Earth has changed over time.
C、Hot underground gasses created clouds, which formed the Earth’s atmosphere.
D、Plant growth depended on oxygen in the Earth’s atmosphere.
答案
B
解析
转载请注明原文地址:https://tihaiku.com/zcyy/3910302.html
相关试题推荐
Parentingwasneverapieceofcakeinanyage,butprobablythegreatestso
Parentingwasneverapieceofcakeinanyage,butprobablythegreatestso
Parentingwasneverapieceofcakeinanyage,butprobablythegreatestso
Parentingwasneverapieceofcakeinanyage,butprobablythegreatestso
[originaltext]You’veprobablyheardtheslogan"savethewhales".Doyoukn
[originaltext]You’veprobablyheardtheslogan"savethewhales".Doyoukno
[originaltext]You’veprobablyheardtheslogan"savethewhales".Doyoukno
Thereareseveraldifferentmethodsthatcanbeusedtocreateaforecast.Th
Thereareseveraldifferentmethodsthatcanbeusedtocreateaforecast.Th
Thereareseveraldifferentmethodsthatcanbeusedtocreateaforecast.Th
随机试题
当前我国经济发展势头良好,经济增长的内在机制(theinternalmechanism)不断增强,基本做到了速度、质量和效益的统一。但是我们也要清醒
Preschoolers’InnateKnowledgeMeansTheyCanProbably
[originaltext]Anelderlywomanyesterdaymadealegalclaimagainstadepar
Withtheintroductionofthecomputer,librariestodayarequitedifferentfrom
主变压器复合电压闭锁过流保护当失去交流电压时( )。A.整套保护就不起作用 B
()对于花蕊相当于叶脉对于()()A.蜂蜜;二氧化碳 B.花瓣;叶肉
某公司2010年12月31日资产负债表如表2所示 存货周转次数越多,则说明
磨耗可见于A.当下颌从姿势位闭合,只有少数牙甚至个别牙接触 B.前伸咬合时,前
设有防渗压重铺盖的堤防的护堤地应从()开始起算。A.防渗压重铺盖坡脚线 B.
(2021年真题第2批)下列施工合同实施偏差的处理措施中,属于组织措施的有(
最新回复
(
0
)