gre阅读练习每日一篇(五十三).

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　　掌握了gre阅读里的长难句，到了实战演习的时候了。gre阅读练习每日一篇帮助gre考生循序渐进地进行练习和总结。希望gre考生在进行gre阅读练习时，也按着考试时候的时间规定自己的练习，这样才能有效果。

　　(This passage is from an article published in 1973)

　　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. Therore, 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

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

　　(B) present a reasoned (reasoned: adj.详尽论述的, 理由充分的) prognosis of the status of women in the new United States all-volunteer armed forces

　　(D) analyze rorms in the new United States all-volunteer armed forces necessitated by the increasing number of women in the military

　　(E) 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

　　(A) receiving equal pay for equal work

　　(B) having access to positions of responsibility at most levels

　　(D) beniting from opportunities arising from new noncombat functions

　　(E) 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?

　　(A) The all-volunteer character of the present armed forces

　　(B) The past service records of women who had assignments functionally equivalent to men’s assignments

　　(D) A decline in the proportion of deterrence oriented noncombat assignments

　　(E) Restrictive past policies governing the military assignments open to women

　　20. The “dramatic gains for women” (line 5) 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 (inasmuch as: 因为, 由于) the author puts forward the latter as

　　(A) a public response to achievement of the former

　　(B) the major reason for absence of the former

　　(D) a catalyst for a further extension of the former

　　(E) 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 (called “chondrites”) 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 (some 3.5 billion years later than typical achondrites) 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 (a volcanically active moon of Jupiter), 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 (in view of: adv.考虑到, 由于) 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 fects 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 (escape velocity: n.逃逸速度). 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.

　　(A) I only

　　(B) II only

　　(D) II and III only

　　(E) 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?

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

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

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

　　(E) 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

　　(A) still entirely undetermined

　　(B) less than that of most other achondrites

　　(D) the same as that of typical achondrites

　　(E) greater than that of the Earth

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

　　(A) has probably come from Mars

　　(B) is older than the solar system itself

　　(D) is certainly less than 4 billion years old

　　(E) is a small fragment of an asteroid

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

　　(A) What is the precise age of the solar system?

　　(B) How did shergottites get their name?

　　(D) How volcanically active is the planet Jupiter?

　　(E) 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

　　(A) planet’s size

　　(B) planet’s distance from Earth

　　(D) proximity of the planet to its moons

　　(E) 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?

　　(A) Crystals

　　(B) Chondrules

　　(D) Sodium

　　(E) Sulfur

答案：17-27：BEABACBCEDB

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