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 accounts for the low-lying, flat surface of Mars’s north? On Earth’s surface, higher- and lower-lying areas have different
What accounts for the low-lying, flat surface of Mars’s north? On Earth’s surface, higher- and lower-lying areas have different
admin
2020-03-28
19
问题
What accounts for the low-lying, flat surface of Mars’s north? On Earth’s surface, higher- and lower-lying areas have different types of crust: one, thin and dense, is pulled toward Earth’s center more strongly by gravity, and the planet’s water naturally comes to sit over it, creating oceans. The processes that generate this oceanic crust drive plate tectonics.
Is Mars’s north similarly characterized by a sort of crust different from other areas of the planet? Some researchers do see signs of tectonic activity surrounding the northern basin that suggest that it was created through the formation of new crust, like ocean basins on Earth. However, McGill points to northern bedrock structures that predate the features said to mark the start of the tectonic process. McGill instead believes that through some novel mechanism the ancient surface sank to its current depth as a single unit. This would explain why features around the basin’s edge, which would have formed as the surface dropped, seem to be younger than structures at its floor.
The third possibility is that the northern lowlands result from impacts. Some researchers suggest they formed as a series of big overlapping impact craters. Others arguing that the odds against such a pattern of impacts are large, postulate a single event—the impact of an object bigger than any asteroid the solar system now contains.
The primary purpose of the passage is to
选项
A、explore an analogy between aspects of the geology of Mars and the geology of Earth.
B、describe how a certain feature of Mars’s surface formed.
C、point out the effect that new data has had on a scientific investigation.
D、summarize potential explanations of a large-scale geological feature.
E、present the rationale for a scientist’s theory and expose some of its weaknesses.
答案
D
解析
a large scale geological feature对应火星北部盆地,potential explanations对应文中三种观点。根据第三段第一句The third possibility可知,文中三种观点均为可能性的推测,没有定论,因此对应该项的potential。
转载请注明原文地址:https://kaotiyun.com/show/RhVO777K
本试题收录于:
GRE VERBAL题库GRE分类
0
GRE VERBAL
GRE
相关试题推荐
Thefollowingquestionspresentasentence,partofwhichorallofwhichisunderlined.Beneaththesentence,youwillfindfiv
Thefollowingquestionspresentasentence,partofwhichorallofwhichisunderlined.Beneaththesentence,youwillfindfiv
Studentsatacertainuniversityhavecomplainedthatsomeoftheirprofessorsdonotprovidecopiesoftheirlecturenotesate
MosteconomistsintheUnitedStatesseemcaptivatedbythespellofthefreemarket.Consequently,nothingseemsgoodornormal
Excessinventory,amassiveproblemformanybusinesses,hasseveralcauses,someofwhichareunavoidable.Overstocksmayaccum
Attheendofthenineteenthcentury,arisinginterestinNativeAmericancustomsandanincreasingdesiretounderstandNative
ProposalsforextendingtheUnitedStatesschoolyeartobringitmoreinlinewithitsEuropeanandJapanesecounterpartsareo
Crimesaremainlycommittedbytheyoung,andforthisreasonmerelyincreasingthenumberofpoliceofficersorexpenditureson
Acommonmisconceptionisthatuniversityhospitalsarebetterthancommunityorprivatehospitals.Infact,universityhospital
A、itfailstodescribespaceonanon-locallevel,complicatingattemptstodeterminethegeometricalmodeloftheuniverseB、it
随机试题
桃核承气汤证的病机是
商阳穴位于
举例说明抗心律失常药的分类。
不属于现代机械安全应具有的特性是()。
建筑装饰装修工程多采用()为计算基础的计价。
下列关于地铁防火的相关描述错误的有()。
从规避投资风险的角度看,债券投资组合的主要形式有( )。
简述影响服从的因素。
2016年某市一次有关市民邻里关系的调查显示,在受访的951位市民中,“没有邻居”的有6位。“有邻居”的受访市民中,对邻居表示“了解”的占55.8%(“了解”分“很了解”和“部分了解”,占比分别为26.9%和28.9%),其余的表示“不了解”;对邻里关系表
下列数据结构中,能够按照“先进后出”原则存取数据的是()。
最新回复
(
0
)