-
最权威的国际教育服务平台
2012
年
12
月
2
日
托福阅读真题解析
阅读
1
版本
1
：宇
宙的两个理论，一个说物质会变化但总量不变，一个是会膨胀，最后说一个
遥远的恒星的
发现说明后一个理论更正确；
<
/p>
版本
2
：讲的是
universe expanding
的两种理论，一个是
density
在变小。另一种是
density
不变。因为不断
new creation
补充变大
的空间，然后发现了一种
q.
它表明前一种理
< br>论更可信。
解析：
big-bang model
widely held theory of the
evolution of the universe. Its essential feature
is the
emergence of the universe from a
state of extremely high temperature and density-
the
so-called big bang that occurred at
least 10,000,000,000 years ago. Although this type
of
universe was proposed by Alexander
Friedmann and Abbé
Georges Lema?tre in
the
1920s, the modern version was
developed by George Gamow and colleagues in the
1940s.
The big-bang model is based
on two assumptions. The first is that Albert
Einstein's
general theory of relativity
correctly describes the gravitational interaction
of all matter.
The second assumption,
called the cosmological principle, states that an
observer's view
of the universe depends
neither on the direction in which he looks nor on
his location. This
principle applies
only to the large-scale properties of the
universe, but it does imply that
the
universe has no edge, so that the big-bang origin
occurred not at a particular point in
space but rather throughout space at
the same time. These two assumptions make it
possible to calculate the history of
the cosmos after a certain epoch called the Planck
time.
Scientists have yet to determine
what prevailed before Planck time.
According to
the big-bang model, the universe expanded rapidly
from a highly
compressed primordial
state, which resulted in a significant decrease in
density and
temperature. Soon
afterward, the dominance of matter over antimatter
(as observed today)
may have been
established by processes that also predict proton
decay. During this stage
many types of
elementary particles may have been present. After
a few seconds, the
universe cooled
enough to allow the formation of certain nuclei.
The theory predicts that
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definite amounts of
hydrogen, helium, and lithium were produced. Their
abundances
agree with what is observed
today. About 1,000,000 years later the universe
was
sufficiently cool for atoms to
form. The radiation that also filled the universe
was then free
to travel through space.
This remnant of the early universe is the
microwave background
radiation (three
degree background radiation) discovered in 1965 by
Arno A. Penzias and
Robert W.
Wilson.
In addition to accounting for the
presence of ordinary matter and radiation, the
model
predicts that the present
universe should also be filled with neutrinos,
fundamental
particles with no mass or
electric charge. The possibility exists that other
relics from the
early universe may
eventually be discovered.
expanding
universe
dynamic state of the extragalactic
realm, the discovery of which has transformed
20th-century cosmology. The development
of general relativity and its application to
cosmology by Albert Einstein, Wilhelm
de Sitter, and other theoreticians, along with the
detection of extragalactic redshift (a
shift to the longer wavelengths of light from
galaxies
beyond the Milky Way) by
VestoSlipher, led to the realization in the 1920s
that all galaxies
are receding. Edwin
Hubble correlated these observations in
mathematical form to
provide evidence
that the universe is expanding. The discovery of
the 2.7 K background
radiation in 1965
by Arno A. Penzias and Robert W. Wilson is
regarded as convincing
evidence that
the universe originated approximately 15 billion
years ago in a very dense
and hot state
referred to as the big bang (seebig-bang
model).
Observations so far have not succeeded
in determining whether the universe is open
(of infinite extent in space) or closed
(of finite extent) and whether the universe in the
future will continue to expand
indefinitely or will eventually collapse back into
an extremely
dense, congested state.
See also cosmology.
阅读
2
版本
1
：草
原上的三种食草动物，斑马羊，还有一个
B
。他们吃草的不同的
部分。把草的各
个部分坐对比，斑马的
diet
最没营养，因为蛋白质少，题目问你斑马怎么吃饱。羊吃的最有营
养题目问你为
什么。然后讲过渡放牧，他们之间没有竞争，相处的较和谐。羊反而会
prefer
那
些已经被斑马吃过的草地而不是全新的草地
版本
2
：讲了非洲的一片地区有很多种大型食草的哺乳动物，斑马，羚羊和一个什么
white
的东西看上去像牛他们在吃草的时候会互补，
因为他们吃的是植物不同的地方。
其中羚羊获取得
营养
的最多，斑马的营养最少，但是斑马靠一个大的胃储存的多。
解析：
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与
OG
测试题非常相似，请参考
--
Feeding Habits
of East African Herbivores
Buffalo, zebras, wildebeests, topi, and
Thomson's gazelles live in huge groups that
together make up some 90 percent of the
total weight of mammals living on the Serengeti
Plain of East Africa. They are all
herbivores (plant-eating animals), and they all
appear to be
living on the same diet of
grasses, herbs, and small bushes. This appearance,
however, is
illusory. When biologist
Richard Bell and his colleagues analyzed the
stomach contents of four
of the five
species (they did not study buffalo), they found
that each species was living on a
different part of the vegetation. The
different vegetational parts differ in their food
qualities:
lower down, there are
succulent, nutritious leaves; higher up are the
harder stems. There are
also sparsely
distributed, highly nutritious fruits, and Bell
found that only the Thomson's
gazelles
eat much of these. The other three species differ
in the proportion of lower leaves and
higher stems that they eat: zebras eat
the most stem matter, wildebeests eat the most
leaves,
and topi are intermediate.
How are we to
understand their different feeding preferences?
The answer lies in two
associated
differences among the species, in their digestive
systems and body sizes.
According to
their digestive systems, these herbivores can be
divided into two categories: the
nonruminants (such as the zebra, which
has a digestive system like a horse) and the
ruminants (such as the wildebeest,
topi, and gazelle, which are like the cow).
Nonruminants
cannot extract much energy
from the hard parts of a plant; however, this is
more than made up
for by the fast speed
at which food passes throughtheir guts. Thus, when
there is only a short
supply of poor-
quality food, the wildebeest, topi, and gazelle
enjoy an advantage. They are
ruminants
and have a special structure (the rumen) in their
stomachs, which contains
microorganisms
that can break down the hard parts of plants. Food
passes only slowly through
the
ruminant's gut because ruminating-digesting the
hard parts-takes time. The ruminant
continually regurgitates food from its
stomach back to its mouth to chew it up further
(that is
what a cow is doing when
almost to a liquid can the food pass
through the rumen and on through the gut. Larger
particles
cannot pass through until
they have been chewed down to size. Therefore,
when food is in
short supply, a
ruminant can last longer than a nonruminant
because it can derive more
energy out
of the same food. The difference can partially
explain the eating habits of the
Serengeti herbivores. The zebra chooses
areas where there is more low-quality food. It
migrates first to unexploited areas and
chomps the abundant low-quality stems before
moving
on. It is a fast-in/fast-out
feeder, relying on a high output of incompletely
digested food. By the
time the
wildebeests (and other ruminants) arrive, the
grazing and trampling of the zebras will
have worn the vegetation down. As the
ruminants then set to work, they eat down to the
lower,
leafier parts of the vegetation.
All of this fits in with the differences in
stomach contents with
which we began.
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