Directions: Each passage in this section is followed by a group of questions to be answered on the basis of what is stated or implied in the passage. For some of the questions, more than one of the choices could conceivably answer the question. However, you are to choose the best answer, that is, the response that most accurately and completely answers the question, and blacken the corresponding space on your answer sheet.
　　Oil companies needs offshore platforms primarily because the oil or natural gas the companies extract from the ocean floor has to be processed before pumps can be used to move the substances ashore. But because processing crude (unprocessed oil or gas) on a platform rather than at facilities onshore exposes workers to the risks of explosion and to an unpredictable environment, researchers are attempting to diminish the need for human labor on platforms and even to eliminate platforms altogether by redesigning two kinds of pumps to handle crude. These pumps could then be used to boost the natural pressure driving the flow of crude, which, by itself, is sufficient only to bring the crude to the platform, located just above the wellhead. Currently, pumps that could boost this natural pressure sufficiently to drive the crude through a pipeline to the shore do not work consistently because of the crude’s content. Crude may consist of oil or natural gas in multiphase states—combinations of liquids, gases, and solids under pressure—that do not reach the wellhead in constant proportions. The flow of crude oil, for example, can change quickly from 60 percent liquid to 70 percent gas. This surge in gas content causes loss of “head”, or pressure inside a pump, with the result that a pump can no longer impart enough energy to transport the crude mixture through the pipeline and to the shore.
　　Of two pumps being redesigned, the positive-displacement pump is promising because it is immune to sudden shifts in the proportion of liquid to gas in the crude mixture. But the pump’s design, which consists of a single or twin screw pushing the fluid from one end of the pump to the other, brings crude into close contact with most parts of the pump, and thus requires that it be made of expensive, corrosion-resistant material. The alternative is the centrifugal pump, which has a rotating impeller that sucks fluid in at one end and forces fluid out at the other. Although this pump has a proven design and has worked for years with little maintenance in waste-disposal plants, researchers have discovered that because the swirl of its impeller separates gas out from the oil that normally accompanies it, significant reductions in head can occur as it operates.
　　Research in the development of these pumps is focused mainly on trying to reduce the cost of the positive-displacement pump and attempting to make the centrifugal pump more tolerant of gas. Other researchers are looking at ways of adapting either kind of pump for use underwater, so that crude could be moved directly from the sea bottom to processing facilities onshore, eliminating platforms.
　　1. Which one of following best expresses the main idea of the passage?
　　(A) Oil companies are experimenting with technologies that may help diminish the danger to workers from offshore crude processing.
　　(B) Oil companies are seeking methods of installing processing facilities underwater.
　　(C) Researchers are developing several new pumps designed to enhance human labor efficiency in processing facilities.
　　(D) Researchers are seeking to develop equipment that would preempt (to replace with something considered to be of greater value or priority: take precedence over) the need for processing facilities onshore.
　　(E) Researchers are seeking ways to separate liquids from gases in crude in order to enable safer processing.
　　2. The passage supports which one of the following statements about the natural pressure driving the flow of crude?
　　(A) It is higher than that created by the centrifugal pump.
　　(B) It is constant regardless of relative proportions of gas and liquid.
　　(C) It is able to carry the crude only as far as the wellhead.
　　(D) It is able to carry the crude to the platform.
　　(E) It is able to carry the crude to the shore.
　　3. Which one of the following best describes the relationship of the second paragraph to the passage as a whole?
　　(A) It offers concrete detail designed to show that the argument made in the first paragraph is flawed.
　　(B) It provides detail that expands upon the information presented in the first paragraph.
　　(C) It enhances the author’s discussion by objectively presenting in detail the pros and cons of a claim made in the first paragraph.
　　(D) It detracts from the author’s discussion by presenting various problems that qualify the goals presented.
　　(E) It modifies an observation made in the first paragraph by detailing viewpoints against it.
　　4. Which one of the following phrases, if substituted for the word “head” in line 47, would LEAST change the meaning of the sentence?
　　(A) the flow of the crude inside the pump
　　(B) the volume of oil inside the pump
　　(C) the volume of gas inside the pump
　　(D) the speed of the impeller moving the crude
　　(E) the pressure inside of the pump
　　5. With which one of the following statements regarding offshore platforms would the author most likely agree?
　　(A) If a reduction of human labor on offshore platform is achieved, there is no real need to eliminate platforms altogether.
　　(B) Reducing human labor on offshore platforms is desirable because researchers’ knowledge about the transportation of crude is dangerously incomplete.
　　(C) The dangers involved in working on offshore platforms make their elimination a desirable goal.
　　(D) The positive-displacement pump is the better alternative for researchers, because it would allow them to eliminate platforms altogether.
　　(E) Though researchers have succeeded in reducing human labor on offshore platforms, they think that it would be inadvisable to eliminate platforms altogether, because these platforms have other uses.
　　6. Which one of the following can be inferred from the passage about pumps that are currently available to boost the natural pressure of crude?
　　(A) The efficiency of these pumps depends on there being no gas in the flow of crude.
　　(B) These pumps are more efficient when the crude is less subject to sudden increases in the proportion of gas to liquid.
　　(C) A sudden change from solid to liquid in the flow of crude increases the efficiency of these pumps.
　　(D) The proportion of liquid to gas in the flow of crude does not affect the efficiency of these pumps.
　　(E) A sudden change from liquid to gas in the flow of crude increases the risk of explosion due to rising pressure inside these pumps.
　　7. The passage implies that the positive-displacement pump differs from the centrifugal pump in that the positive-displacement pump
　　(A) is more promising, but it also is more expensive and demands more maintenance
　　(B) is especially well research, since it has been used in other settings
　　(C) involves the use of a single or twin screw that sucks fluid in at one end of the pump
　　(D) is problematic because it cause rapid shifts from liquid to gas content in crude
　　(E) involves exposure of many parts of the pump to crude
　　8. The passage implies that the current state of technology necessitates that crude be moved to shore
　　(A) in a multiphase state
　　(B) in equal proportions of gas to liquid
　　(C) with small proportions of corrosive material
　　(D) after having been processed
　　(E) largely in the form of a liquid