Reading Comprehension

试题详情

文章:

    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 longstanding 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.

题目:

The author mentions the fact that baryons are the source of stars' luminosity primarily in order to explain

选项:

A、how astronomers determine that some galaxies contain fewer stars per unit volume than do others
B、how astronomers are able to calculate the total luminosity of a galaxy
C、why astronomers can use galactic luminosity to estimate baryonic mass
D、why astronomers' estimates of baryonic mass based on galactic luminosity are more reliable than those based on spectroscopic studies of helium
E、how astronomers know bright galaxies contain more baryons than do dim galaxies

答案:

C

提问:

根据问题找baryons,可以定位到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.这一句。然后就看选项了。 根据and so their numbers can be estimated based on how luminous galaxies are,B最沾边,于是就选了B了。 听了之前答疑的录音,发现是自己定位错了。 定位句应该是Baryons前面的那一句话,因为问题问的是in order to。 可是将这个例子具体内容里面,“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.”中不是由两个句子么?(and therefore……) “therefore”让我感觉就是在提出这个例子的作用的,当时就没想到还应该看看这个fact的前面那句。 我知道自己这样做又主观了,可是therefore的吸引力太大了……我该怎么克服这类错误呢?请老师指点!谢谢!
评分: -1
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提问:

剩B和C不知道怎么排除
评分: 0
浏览: 97

提问:

根据问题找baryons,可以定位到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.这一句。然后就看选项了。 根据and so their numbers can be estimated based on how luminous galaxies are,B最沾边,于是就选了B了。 听了之前答疑的录音,发现是自己定位错了。 定位句应该是Baryons前面的那一句话,因为问题问的是in order to。 可是将这个例子具体内容里面,“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.”中不是由两个句子么?(and therefore……) “therefore”让我感觉就是在提出这个例子的作用的,当时就没想到还应该看看这个fact的前面那句。 我知道自己这样做又主观了,可是therefore的吸引力太大了……我该怎么克服这类错误呢?请老师指点!谢谢!
评分: -1
浏览: 103

提问:

剩B和C不知道怎么排除
评分: 0
浏览: 97
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