【正文】 hot rock of the mantle is a solid, under the tremendous pressure of the crust and overlying rock of the mantle, it flows like a viscous liquid. The mantle’s motions, analogous to those in a pot of boiling water, cool the mantle by carrying hot material to the surface and returning cooler material to the depths. When the edge of one plate bends under another and its cooler material is consumed in the mantle, volcanic activity occurs as molten lava rises from the downgoing plate and erupts through the overlying one. Most volcanoes occur at plate boundaries. However, certain “misplaced” volcanoes far from plate edges result from a second, independent mechanism that cools the deep interior of Earth. Because of its proximity to Earth’s core, the rock at the base of the mantle is much hotter than rock in the upper mantle. The hotter the mantle rock is, the less it resists flowing. Reservoirs of this hot rock collect in the base of the mantle. When a reservoir is sufficiently large, a sphere of this hot rock forces its way up through the upper mantle to Earth’s surface, creating a broad bulge in the topography. The “mantle plume” thus formed, once established, continues to channel hot material from the mantle base until the reservoir is emptied. The surface mark of an established plume is a hot spot—an isolated region of volcanoes and uplifted terrain located far from the edge of a surface plate. Because the source of a hot spot remains fixed while a surface plate moves over it, over a long period of time an active plume creates a chain of volcanoes or volcanic islands, a track marking the position of the plume relative to the moving plate. The natural history of the Hawaiian island chain clearly shows the movement of the Pacific plate over a fixed plume.Q22: The passage is primarily concerned with discussing A. the position of Earth’s mantleB. how the Hawaiian Islands were createdC. what causes Earth’s surface plates to moveD. two different mechanisms by which volcanoes are formedE. why most volcanoes occur at plate boundariesQ23:It can be inferred from the passage that a chain of volcanoes created by a mantle plume would most likely be characterized byA. a curved outlineB. constituent volcanoes that differ from each other in ageC. occurrence near a plate boundary where one plate bends under anotherD. appearance near many other volcanic chainsE. rocks with a wide range of chemical positionQ24:The author’s reference to the Hawaiian Islands serves primarily toA. provide an example of a type of volcanic activity that does not occur elsewhereB. identify the evidence initially used to establish that the Pacific plate movesC. call into question a theory about the source of the volcanoes that created the Hawaiian IslandsD. illustrate the distance from plate edges at which volcanoes typically appearE. provide an example of how mantle plumes manifest themselves on Earth’s surfaceQ25:According to the passage, a hot spot on Earth’s surface is an indication of which of the following?A. An untapped reservoir of hot rock in the base of the mantleB. Volcanic activity at the edge of a plateC. Solid mantle rock under tremendous pressureD. The occurrence of a phenomenon unique to the Pacific plateE. A plume of hot mantle rock originating near Earth’s coreGWD7Q26:The Organization of Petroleum Exporting Countries (OPEC) had long been expected to announce a reduction in output to bolster sagging oil prices, but officials of the organization just recently announced that the group will pare daily production by million barrels by the beginning of next year, but only if nonOPEC nations, including Norway, Mexico, and Russia, were to trim output by a total of 500,000 barrels a day.A. year, but only if nonOPEC nations, including Norway, Mexico, and Russia, were to trim outputB. year, but only if the output of nonOPEC nations, which includes Norway, Mexico, and Russia, is trimmedC. year only if the output of nonOPEC nations, including Norway, Mexico, and Russia, would be trimmedD. year only if nonOPEC nations, which includes Norway, Mexico, and Russia, were trimming outputE. year only if nonOPEC nations, including Norway, Mexico, and Russia, trim outputGWD7Q27:A significant number of plex repair jobs carried out by Ace Repairs have to be reworked under the pany’s warranty. The reworked jobs are invariably satisfactory. When initial repairs are inadequate, therefore, it is not because the mechanics lack petence。 rather, there is clearly a level of focused concentration that plex repairs require that is elicited more reliably by rework jobs than by firsttime jobs.The argument above assumes which of the following?A. There is no systematic difference in membership between the group of mechanics who do firsttime jobs and the group of those who do rework jobs.B. There is no pany that successfully petes with Ace Repairs for plex repair jobs.C. Ace Repairs’ warranty is good on firsttime jobs but does not cover rework jobs.D. Ace Repairs does not in any way penalize mechanics who have worked on plex repair jobs that later had to be reworked.E. There is no category of repair jobs in which Ace Repairs invariably carries out firsttime jobs satisfactorily.Q28: GWD210Environmentalist: The use of snowmobiles in the vas