首页
登录
职称英语
In addition to conventional galaxies, the universe contains very dim galaxies th
In addition to conventional galaxies, the universe contains very dim galaxies th
游客
2024-01-12
6
管理
问题
In addition to conventional galaxies, the universe contains very dim galaxies that until recently went unnoticed by astronomers. Possibly as numerous as conventional galaxies, these galaxies have the same general shape and even the same approximate number of stars as a common type of conventional galaxy, the spiral, but tend to be much larger. Because these galaxies’ mass is spread out over larger areas, they have far fewer stars per unit volume than do conventional galaxies. Apparently these low-surface-brightness galaxies, as they are called, take much longer than conventional galaxies to condense their primordial gas and convert it to stars—that is, they evolve much more slowly.
These galaxies may constitute an answer to the long-standing puzzle of the missing baryonic mass in the universe. Baryons—subatomic particles that are generally protons or neutrons—are the source of stellar, and therefore galactic, luminosity, and so their numbers can be estimated based on how luminous galaxies are. However, the amount of helium in the universe, as measured by spectroscopy, suggests that there are far more baryons in the universe than estimates based on galactic luminosity indicate. Astronomers have long speculated that the missing baryonic mass might eventually be discovered in intergalactic space or as some large population of galaxies that are difficult to detect. [br] The primary purpose of the passage is to
选项
A、describe a phenomenon and consider its scientific significance
B、contrast two phenomena and discuss a puzz ing difference between them
C、identify a newly discovered phenomenon anc explain its origins
D、compare two classes of objects and discuss the physical properties of each
E、discuss a discovery and point out its inconsistency with existing theory
答案
A
解析
Main idea
This question requires understanding, in broad terms, the purpose of the passage as a whole. The first paragraph describes a phenomenon: the discovery of dim galaxies and some of their general attributes. The second paragraph describes how this discovery may help astronomers to solve a long-standing puzzle about the baryonic mass of the universe.
A Correct. The passage describes the phenomenon of dim galaxies and describes their significance in solving the longstanding puzzle of the missing baryonic mass in the universe.
B Although the passage discusses the puzzling difference between the two estimates of baryonic mass, this option does not account for the broader topic of dim galaxies.
C While the passage identifies the newly discovered phenomenon of dim galaxies, it does not offer a significant explanation for these galaxies’ origins.
D Although the passage compares dim an 1 conventional galaxies in the first paragraph, this option does not account for the important detail that dim galaxies may help solve a long-standing puzzle.
E The discovery of dim galaxies discussed in the passage is not said to be inconsistent with any existing scientific theory.
The correct answer is A.
转载请注明原文地址:https://tihaiku.com/zcyy/3357236.html
相关试题推荐
Woodsmokecontainsdangeroustoxinsthatcausechangesinhumancells.Becausew
Ithasbeenhypothesizedthatmuchofthematterintheuniverseis"dark,"i.e
Thetoxinproducedbycertainmarinesnailscontainsvariousproteins,oneofwh
Essayist:Theexistenceofamoralorderintheuniverse—i.e.,anorderinwhi
Ms.Chambersisamongtheforecasterswhopredictthattherateofadditiontoa
Inthe1950’sastronomersweredividedbetweenthosewhobelievedtheuniverseb
Untilrecentlymostastronomersbelievedthatthespacebetweenthegalaxies
Untilrecentlymostastronomersbelievedthatthespacebetweenthegalaxies
Untilrecentlymostastronomersbelievedthatthespacebetweenthegalaxies
Untilrecentlymostastronomersbelievedthatthespacebetweenthegalaxies
随机试题
[originaltext]W:Youhaven’tseenmygymbag,haveyou?M:Haveyoucheckedba
AccordingtoBT’sfuturologist,IanPearson,theseareamongthedevelopment
消防炮安装应符合设计要求,且安装后应进行供水管线系统试压、冲洗。
土的酸碱度测定时,应进行温度补偿操作。()
在《国际评估准则2017》的《国际评估准则104——价值类型》,价值类型包括(
A.黄绿色B.脓性混浊C.金黄色D.无色透明E.黄色正常妊娠早期羊水呈
低渗性脱水伴休克,补液时应首选A:3%氯化钠溶液 B:10%葡萄糖盐水 C:
产品售后服务包括( )。A.提供给消费者多种可供选择的服务价格和服务合同 B
将会计准则与计算机语言结合的最新公认标准和技术的语言,是()。A、EMLB、A
投资项目决策分析与评价的基本要求包括贯彻落实科学发展观、资料数据准确可靠和()
最新回复
(
0
)