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 Moon, which has undergone a distinct and complex geological history, presents a striking appearance. The moon may be divided
The Moon, which has undergone a distinct and complex geological history, presents a striking appearance. The moon may be divided
admin
2009-01-05
47
问题
The Moon, which has undergone a distinct and complex geological history, presents a striking appearance. The moon may be divided into two major terrains: the maria (dark lowlands) and the terrace (bright high lands). The contrast in the reflectivity (the capability of reflecting light) of these two terrains suggested to many early observers that the two terrains might have different compositions, and this supposition was con firmed by missions to the Moon such as Surveyor and Apollo. One of the most obvious differences between the terrains is the smoothness of the maria in contrast to the roughness of the highlands. This roughness is mostly caused by the abundance of craters; the highlands are completely covered by large craters (greater than 40- 50km in diameter), while the craters of the maria tend to be much smaller. It is now known that the vast majority of the Moon’s craters Were formed by the impact of solid bodies with the lunar surface.
Most of the near side of the Moon was thoroughly mapped and studied from telescopic pictures years before the age of space exploration. Earth-based telescopes can resolve objects as small as a few hundred meters on the lunar surface. Close observation of craters, combined with the way the Moon diffusely reflects sunlight, led to the understanding that the Moon is covered by a surface layer, or regolith, that overlies the solid rock of the Moon. Telescopic images permitted the cataloging of a bewildering array of land forms. Craters were studied for clues to their origin; the large circular maria were mapper. Wispy marks on the surface (known as rays) emanating from certain craters were seen. Strange, sinuous features were observed in the maria. Although various land forms were catalogued, the majority of astronomers’ attention was fixed on craters and their origins.
Astronomers have known for a fairly long time that the shape of craters changes as they increase in size. Small craters with diameters of less than 10-15km have relatively simple shapes. They have rim crests that are elevated above the surrounding terrain, smooth, howl-shaped interiors, and depths that are about one-fifth to one-sixth their diameters. The complexity of shape increases for larger craters.
According to the passage lunar researchers have focused mostly on ______.
选项
A、the possibility of finding water on the Moon
B、the lunar regolith
C、cataloging various land formations
D、craters and their origins
答案
D
解析
细节理解题。由文章第二段最后一句话“Although various land forms were catalogued,the majority of astronomers attention was fixed on craters and their origins.”可知,“弹坑及其起源”是研究者主要关心的问题。
转载请注明原文地址:https://kaotiyun.com/show/nSBK777K
0
专业英语四级
相关试题推荐
Thebookisdead.Technologyhaskilledit.Thelibrariesoftheworldaredoomingtobecomemuseums.Americans,however,【M1】___
Fundingpublictransitisoneofthebiggestproblemsfacingcitiestoday.Oftenthetroubleisthatafewhigh-cost,low-rider
Thebrainsofchildrenareaffectedbyfamilyviolenceinthesamewayascombataffectssoldiers,accordingtoastudy.Inbot
Tolive,learn,andworksuccessfullyinanincreasing【S1】______complexandinformation-richsociety,studentsmustbeable
ComputerCrimeI.IntroductionCurrentsituation:theincreaseinthenumberandtypesofcomputercrimeII.【T1】______
Ifyousmokeandyoustilldon’tbelievethatthere’sadefinitelinkbetweensmokingandbronchialtroubles,heartdiseaseand
Thefollowingtwoexcerptsareaboutethicsoftoday’smassmedia,which,despitetheirhugeinfluence,offerthereadersmorea
A、Meetingtheirdesiretolearnontheirown.B、Improvingtheirlearningabilitiesgreatly.C、Substitutingboringclassroomlear
Whenpreparingelementaryschooltest,careshouldbetaken______.
Thetwoscholarsworkedatthetaskofwritingaprefacetothenewdictionaryforthreehours______lastnight.
随机试题
任意周期信号都可以用()表达。
A.胆红素B.肌酐C.磷脂酰胆碱/鞘磷脂D.脂肪细胞E.淀粉酶判断胎儿肺成熟度,可检查的羊水项目是
治疗亡阳虚脱及中脏寒盛者均可以用的药组是
(2006年)若则a与b的值是()。
质量监督人员()。
“预提费用”账户属于( )。
来料加工与进料加工的区别在于()。
即使取得票据的原因关系无效,对票据关系也不会发生影响,票据的这个特征说明票据是一种( )。
(2011年真题)甲承包经营某国有企业内部招待所。由于招待所生意不好,甲找来乙协商,由甲负责提供场所和管理,乙负责物色卖淫女。乙找来6名女性后,甲随即安排这些女性从事卖淫活动,并抽取50%的嫖资作为“管理费"。甲、乙平分非法所得。公安机关接到举报后,拘留了
Hehasneverworriedabouthispropertiesbecausehehas______themagainstdisastersandtheft.
最新回复
(
0
)