【文章內(nèi)容簡(jiǎn)介】 of study 19. The passage suggests that the author would regard which of the following areas of inquiry as most likely to reveal the slaves39。 cultural continuities with Africa? (A) The means by which Blacks disseminated their folktales in nieenthcentury America (B) Specific regional differences in the styles of delivery used by the slaves in telling folktales (C) The functional meaning of Black folktales in the lives of White children raised by slaves (D) The specific way the slaves used folktales to impart moral teachings to their children (E) The plexities of plot that appear most frequently in the slaves39。 tales 20. Which of the following techniques is used by the author in developing the argument in the passage? 中國(guó)最大的管理資源中心 (大量免費(fèi)資源共享 ) 第 12 頁(yè) 共 25 頁(yè) (A) Giving a cliche a new meaning (B) Pointedly refusing to define key terms (C) Alternately presenting generalities and concrete details (D) Concluding the passage with a restatement of the first point made in the passage (E) Juxtaposing statements of what is not the case and statements of what is the case The energy contained in rock within the earth39。s crust represents a nearly unlimited energy source, but until recently mercial retrieval has been limited to underground hot water and/or steam recovery systems. These systems have been developed in areas of recent volcanic activity, where high rates of heat flow cause visible eruption of water in the form of geysers and hot springs. In other areas, however, hot rock also exists near the surface but there is insufficient water present to produce eruptive phenomena. Thus a potential hot dry rock (HDR) reservoir exists whenever the amount of spontaneously produced geothermal fluid has been judged inadequate for existing mercial systems. 中國(guó)最大的管理資源中心 (大量免費(fèi)資源共享 ) 第 13 頁(yè) 共 25 頁(yè) As a result of the recent energy crisis, new concepts for creating HDR recovery systemswhich involve drilling holes and connecting them to artificial reservoirs placed deep within the crustare being developed. In all attempts to retrieve energy from HDR39。s, artificial stimulation will be required to create either sufficient permeability or bounded flow paths to facilitate the removal of heat by circulation of a fluid over the surface of the rock. The HDR resource base is generally defined to include crustal rock that is hotter than 150℃ , is at depths less than ten kilometers, and can be drilled with presently available equipment. Although wells deeper than ten kilometers are technically feasible, prevailing economic factors will obviously determine the mercial feasibility of wells at such depths. Rock temperatures as low as 100℃ may be useful for space heating。 however, for producing electricity, temperatures GREater than 200℃ are desirable. The geothermal gradient, which specifically determines the depth of drilling required to reach a desired temperature, is a major factor in the recoverability of geothermal resources. Temperature gradient maps generated from oil and gas well temperaturedepth records kept by the American Association of Petroleum Geologists suggest that tappable hightemperature gradients are distributed all across the United States. (There are many areas, however, for which no temperature gradient records exist.) 中國(guó)最大的管理資源中心 (大量免費(fèi)資源共享 ) 第 14 頁(yè) 共 25 頁(yè) Indications are that th