|
Q37:
It can be inferred from the passage that which of the following is an accurate physical description of typical low-surface-brightness galaxies?
They are large spiral galaxies containing fewer stars than do conventional galaxies.
They are compact but very dim spiral galaxies.
They are diffuse spiral galaxies that occupy a large volume of space.
They are small, young spiral galaxies that contain a high proportion of primordial gas.
They are large, dense spirals with low luminosity
答案为d 这里small不对啊 我选a
只要看这里就很明显了
these galaxies have the
same general shape and even
the same approximate number
(10) 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
(15) larger areas, they have far
fewer stars per unit volume
没可能小阿？ 请教。
以下是原文：
Q35 to Q37:
In addition to conventional
galaxies, the universe contains
very dim galaxies that until
Line recently went unnoticed by
(5) astronomers. Possibly as
numerous as conventional gal-
axies, these galaxies have the
same general shape and even
the same approximate number
(10) 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
(15) larger areas, they have far
fewer stars per unit volume
than do conventional galaxies.
Apparently these low-surface-
brightness galaxies, as they
(20) 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.
(25) These galaxies may
constitute an answer to the long-
standing puzzle of the missing
baryonic mass in the universe.
Baryons—subatomic particles
(30) 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
(35) luminous galaxies are. How-
ever, the amount of helium
in the universe, as measured
by spectroscopy, suggests
that there are far more baryons
(40) in the universe than estimates
based on galactic luminosity
indicate. Astronomers have
long speculated that the missing
baryonic mass might eventually
(45) be discovered in intergalactic
space or as some large popu-
lation of galaxies that are difficult
to detect. | 
