手机APP下载

您现在的位置: 首页 > SAT > SAT每日一题 > 正文

SAT官方每日一题附答案和解析[阅读](2019年3月8日)

来源:可可英语 编辑:max   VIP免费外教试听课 |  可可官方微信:ikekenet

Critical Reading>Select an Answer

Light from distant quasars -- early galaxies that shine with tremendous brightness -- has given researchers a new clue to the origin of vast magnetic fields studding today's galaxies: They were running strong when the universe was only a third of its present age.

Astronomers had observed that radio emissions from quasars tend to be angled, or polarized, in such a way that powerful magnetic fields must have twisted them. The greater their distance from Earth, the more polarized their light. But researchers didn't know whether the magnetic fields were part of the quasar or were present in galaxies encountered by quasar light as it made its journey to our telescopes.

So a team led by astronomers from the Swiss Federal Institute of Technology (ETH Zurich) scanned more than 70 of those quasars using the European Southern Observatory's Very Large Telescope in Chile to look for signs of galaxies hiding in front of the quasars. Specifically, they checked for a feature called the magnesium(II) absorption line, a reduction in the intensity of light of a certain wavelength, which is a commonly used indicator that gas from a star-forming galaxy has soaked up that light.

The researchers report that light from quasars showing the magnesium(II) line was more strongly polarized than light from other quasars in the sample. The interpretation: that light did indeed pass through regular galaxies and that it likely acquired its polarization in the process.

They estimated the age of the magnetic galaxies by measuring the red shift of the absorption line -- the observed reddening of light that occurs when galaxies move rapidly apart. The typical red shift of the inferred galaxies corresponded to an age of 5.2 billion years, study author Francesco Miniati says. Precision measurements of the cosmic microwave background peg today's universe at 13.7 billion years old.

Which of the following, if true, would undermine the interpretation offered by the researchers in the fourth paragraph?

A.Another team of astronomers measures the red shifts of magnesium(II) absorption lines and concludes that the galaxies formed when the universe was less than 5.2 billion years old.
B.A new study determines that quasars that are not near star-forming galaxies have high levels of polarized light.
C.A group of astronomers publishes a report that suggests the number of known quasars in the universe is higher than previously documented.
D.A massive galaxy that causes strongly polarized light is found to be situated in front of a quasar.

重点单词   查看全部解释    
cosmic ['kɔzmik]

想一想再看

adj. 宇宙的,广大无边的,无限的

联想记忆
X
单词cosmic 联想记忆:
cosm宇宙+ic表形容词,“…的”→宇宙的
 
previously ['pri:vju:sli]

想一想再看

adv. 先前,在此之前

 
galaxy ['gæləksi]

想一想再看

n. 银河,一群显赫之人

联想记忆
X
单词galaxy 联想记忆:
gala=milk牛奶,milky way=银河系以xy结尾的只有4个单词,xy表示交织在一起,象坐标线一样,银河系也象星星交织在一起。参:neodoxy(n 新学说;新见解);orthodoxy(adj 正统的);heterodoxy(n 非正统;异说)
 
absorption [əb'sɔ:pʃən]

想一想再看

n. 吸收,全神贯注

 
observatory [əb'zə:və.tri]

想一想再看

n. 天文台,气象台,了望台

联想记忆
X
单词observatory 联想记忆:
observe观察+atory表名词,“场所,地点”→天文台
 
critical ['kritikəl]

想一想再看

adj. 批评的,决定性的,危险的,挑剔的
a

 
sample ['sæmpl]

想一想再看

n. 样品,样本
vt. 采样,取样

联想记忆
X
单词sample 联想记忆:
s[=se分开]+ample拿,获得→分开拿出→样品,标本
 
magnetic [mæg'netik]

想一想再看

adj. 有磁性的,有吸引力的,催眠术的

联想记忆
X
单词magnetic 联想记忆:
来自magnet(n 吸铁石)
 
shift [ʃift]

想一想再看

n. 交换,变化,移动,接班者
v. 更替,移

 
institute ['institju:t]

想一想再看

n. 学会,学院,协会
vt. 创立,开始,制

联想记忆
X
单词institute 联想记忆:
in进入,stitute站,建立-站进去;进入建立的状态-创立
 


新东方SAT网络课程:试听更多SAT网络课程>>

发布评论我来说2句

    可可英语官方微信(微信号:ikekenet)

    每天向大家推送短小精悍的英语学习资料.

    添加方式1.扫描上方可可官方微信二维码。
    添加方式2.搜索微信号ikekenet添加即可。