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
What is the talk mainly about?
What is the talk mainly about?
admin
2013-10-11
14
问题
What is the talk mainly about?
The origin of Earth’s moon, the largest moon in the solar system, is still something of a mystery. There are some theories about its origin however. Now, keep in mind that a theory of the moon’s origin has to be consistent with two important facts. The first fact is that the Earth contains a lot of iron, most of it has an iron core. But the moon contains practically no iron. The second fact is that other than the difference in iron content, the moon and Earth are composed of accentually the same minerals, a similarity not shared with any other planet or moon in our solar system.
One of the earliest theories of the moon’s origin, I called it the Capture Theory, proposes that the moon was somehow captured by Earth’s gravitational force. This theory is improbable, however, because it assumes that the moon and Earth formed in different parts of the solar system. If this was true you would expect the moon’s composition to be much different from Earth’s composition, just as all the other planets in the solar system are so different from Earth.
A second theory of the moon’s origin is more promising. It is sometimes referred to as the Mars Theory, because according to this theory, when Earth was still molten, it was struck by a planet about the size of Mars. The impact caused the cores of the two planets to melt together and chunks of Earth’s crust to be thrown out into space. These chunks came together to form the moon. Now, remember, Earth’s crust is low in iron, because the iron is in Earth’s core, but high in various other minerals. This then accounts for why there is little iron but lots of other minerals on the moon.
选项
A、Earth’s moon used to orbit Mars.
B、Mars was captured by the gravitational field of the Sun.
C、A planet the size of Mars collided with Earth.
D、Mars is larger than Earth.
答案
C
解析
转载请注明原文地址:https://jikaoti.com/ti/BUJMFFFM
0
专业英语四级
相关试题推荐
StudentsofUnitedStateshistory,seekingtoidentifythecircumstancesthatencouragedtheemergenceoffeministmovements,ha
It’shardtoconfirmorrefutethatthere’sacausalrelationshipbetweentheamountoffatweeatandtheofheartattacks.
Whatistherelationshipbetweenthespeakers?
Thestudentsandteachersaliketookgreat______attherudewaythepresidentcriticizedlittleTom.
ThatLouiseJohannesisbelievedbymanycriticstobethegreatesttwentieth-centurysculptorisallthemoreremarkablebecaus
Whenaskedto______theageoftheantique,youneedtohaveaspecialknowledgeofthehistory.
VirginiaDeprivestheRighttoVoteofFormerFelonsFouryearshavepassedsinceJenniferMcDanielwasreleasedfromaVirg
OrganicAgricultureTheideathatshoppingisthenewpoliticsiscertainlyenticing.Nevermindtheballotbox:votewithy
Therelationshipbetweenthehomeandmarketeconomieshasgonethroughtwodistinctstages.Earlyindustrializationbeganthep
随机试题
从20世纪60年代中期起,人们大都认为,群体的发展要经过五个阶段的标准程序,这五个阶段包括________、_______、__________、________、________。
6-磷酸果糖激酶-1的别构抑制剂是
分子量最大的免疫球蛋白是
A.青霉素GB.磺胺类药物C.大环内酯类药物D.头孢菌素类药物E.万古霉素对于耐甲氧西林表皮葡萄球菌(MRSE)引起的严重肺部感染最有效的药物为()
关于土工合成材料膨润土垫(GCL)施工质量控制要点的说法,正确的有()。
现有两个电压表、一个电源、一个已知阻值为R0的电阻、一个开关和一些导线,要用以上器材测出未知阻值的电阻Rx.要求:分别画出两种不同方法的电路图;
唯物史观与唯心史观的对立主要表现在()。
设X1,X2,X3,X4,X5是来自总体N(1,4)的简单随机样本,
设曲线y=xn在点(1,1)处的切线交x轴于点(ξn,0),求
A、Donotusethisentrancetoreturnvehiclestothefactory.B、Factoryvehiclesareturninghereallthetime.C、Denotturnhe
最新回复
(
0
)