GRE阅读练习每日一篇(五十三)

　 编辑点评： GRE阅读的方法相信大家已经积累了很多了，本文就为大家提供一些GRE阅读的材料，大家来练一练，把平时学到的东西运用到实际中，也多多积累词汇和句子，提高自己的阅读能力。

　　每天做一些标准的GRE阅读练习，有助于大家在GRE考试的复习过程中不断地进行练习和总结。希望大家在进行GRE阅读练习时，充分运用平时所积累的知识，这样才能有效果。

　　The recent change to all-volunteer armed forces in the United States will eventually produce a gradual increase in the proportion of women in the armed forces and in the variety of women s assignments, but probably not the dramatic gains for women that might have been expected. This is so even though the armed forces operate in an ethos of institutional change oriented toward occupational equality and under the federal sanction of equal pay for equal work. The difficulty is that women are unlikely to be trained for any direct combat operations. A significant portion of the larger society remains uncomfortable as yet with extending equality in this direction. Therefore, for women in the military, the search for equality will still be based on functional equivalence, not identity or even similarity of task. Opportunities seem certain to arise. The growing emphasis on deterrence is bound to offer increasing scope for women to become involved in novel types of noncombat military assignments.

　　17. The primary purpose of the passage is to

　　present an overview of the different types of assignments available to women in the new United States all-volunteer armed forces

　　present a reasoned prognosis of the status of women in the new United States all-volunteer armed forces

　　present the new United States all-volunteer armed forces as a model case of equal employment policies in action

　　analyze reforms in the new United States all-volunteer armed forces necessitated by the increasing number of women in the military

　　analyze the use of functional equivalence as a substitute for occupational equality in the new United States all-volunteer armed forces

　　18. According to the passage, despite the United States armed forces commitment to occupational equality for women in the military, certain other factors preclude women s

　　receiving equal pay for equal work

　　having access to positions of responsibility at most levels

　　drawing assignments from a wider range of assignments than before

　　benefiting from opportunities arising from new noncombat functions

　　being assigned all of the military tasks that are assigned to men

　　19. The passage implies that which of the following is a factor conducive to a more equitable representation of women in the United States armed forces than has existed in the past?

　　The all-volunteer character of the present armed forces

　　The past service records of women who had assignments functionally equivalent to men s assignments

　　The level of awareness on the part of the larger society of military issues

　　A decline in the proportion of deterrence oriented noncombat assignments

　　Restrictive past policies governing the military assignments open to women

　　20. The dramatic gains for women and the attitude, as described in lines 11-12, of a significant portion of the larger society are logically related to each other inasmuch as the author puts forward the latter as

　　a public response to achievement of the former

　　the major reason for absence of the former

　　a precondition for any prospect of achieving the former

　　a catalyst for a further extension of the former

　　a reason for some of the former being lost again

　　Of the thousands of specimens of meteorites found on Earth and known to science, only about 100 are igneous; that is, they have undergone melting by volcanic action at some time since the planets were first formed. These igneous meteorites are known as achondrites because they lack chondrules small stony spherules found in the thousands of meteorites composed primarily of unaltered minerals that condensed from dust and gas at the origin of the solar system. Achondrites are the only known samples of volcanic rocks originating outside the Earth-Moon system. Most are thought to have been dislodged by interbody impact from asteroids, with diameters of from 10 to 500 kilometers, in solar orbit between Mars and Jupiter.

　　Shergottites, the name given to three anomalous achondrites so far discovered on Earth, present scientists with a genuine enigma. Shergottites crystallized from molten rock less than 1.1 billion years ago and were presumably ejected into space when an object impacted on a body similar in chemical composition to Earth.

　　While most meteorites appear to derive from comparatively small bodies, shergottites exhibit properties that indicate that their source was a large planet, conceivably Mars. In order to account for such an unlikely source, some unusual factor must be invoked, because the impact needed to accelerate a fragment of rock to escape the gravitational field of a body even as small as the Moon is so great that no meteorites of lunar origin have been discovered.

　　While some scientists speculate that shergottites derive from Io , recent measurements suggest that since Io s surface is rich in sulfur and sodium, the chemical composition of its volcanic products would probably be unlike that of the shergottites. Moreover, any fragments dislodged from Io by interbody impact would be unlikely to escape the gravitational pull of Jupiter.

　　The only other logical source of shergottites is Mars. Space-probe photographs indicate the existence of giant volcanoes on the Martian surface. From the small number of impact craters that appear on Martian lava flows, one can estimate that the planet was volcanically active as recently as a half-billion years ago and may be active today. The great objection to the Martian origin of shergottites is the absence of lunar meteorites on Earth. An impact capable of ejecting a fragment of the Martian surface into an Earth-intersecting orbit is even less probable than such an event on the Moon, in view of the Moon s smaller size and closer proximity to Earth. A recent study suggests, however, that permafrost ices below the surface of Mars may have altered the effects of impact on it. If the ices had been rapidly vaporized by an impacting object, the expanding gases might have helped the ejected fragments reach escape velocity . Finally, analyses performed by space probes show a remarkable chemical similarity between Martian soil and the shergottites.

　　21. The passage implies which of the following about shergottites?

　　I. They are products of volcanic activity.

　　II. They derive from a planet larger than Earth.

　　III. They come from a planetary body with a chemical composition similar to that of Io.

　　I only

　　II only

　　I and II only

　　II and III only

　　I, II, and III

　　22. According to the passage, a meteorite discovered on Earth is unlikely to have come from a large planet for which of the following reasons?

　　There are fewer large planets in the solar system than there are asteroids.

　　Most large planets have been volcanically inactive for more than a billion years.

　　The gravitational pull of a large planet would probably prohibit fragments from escaping its orbit.

　　There are no chondrites occurring naturally on Earth and probably none on other large planets.

　　Interbody impact is much rarer on large than on small planets because of the density of the atmosphere on large planets.

　　23. The passage suggests that the age of shergottites is probably

　　still entirely undetermined

　　less than that of most other achondrites

　　about 3.5 billion years

　　the same as that of typical achondrites

　　greater than that of the Earth

　　24. According to the passage, the presence of chondrules in a meteorite indicates that the meteorite

　　has probably come from Mars

　　is older than the solar system itself

　　has not been melted since the solar system formed

　　is certainly less than 4 billion years old

　　is a small fragment of an asteroid

　　25. The passage provides information to answer which of the following questions?

　　What is the precise age of the solar system?

　　How did shergottites get their name?

　　What are the chemical properties shared by shergottites and Martian soils?

　　How volcanically active is the planet Jupiter?

　　What is a major feature of the Martian surface?

　　26. It can be inferred from the passage that each of the following is a consideration in determining whether a particular planet is a possible source of shergottites that have been discovered on Earth EXCEPT the

　　planet s size

　　planet s distance from Earth

　　strength of the planet s field of gravity

　　proximity of the planet to its moons

　　chemical composition of the planet s surface

　　27. It can be inferred from the passage that most meteorites found on Earth contain which of the following?

　　Crystals

　　Chondrules

　　Metals

　　Sodium

　　Sulfur

　　答案：17-27：BEABACBCEDB