GMAT考试资料：GWD试题合集（十七）.

　　以下将为正在备战GMAT考试的同学们整理一些经典的GMAT阅读试题，并分多个合集推出，希望能够为正在备考GMAT考试的考生提供或多或少的帮助。

　　9. GWD-7-Q22 to Q25形成火山的两个机理

　　Earth’s surface consists of rigid

　　plates that are constantly shifting and

　　jostling one another. Plate movements

　　Line are the surface expressions of motions

　　(5) in the mantle—the thick shell of rock

　　that lies between Earth’s crust and its

　　metallic core. Although the hot rock of

　　the mantle is a solid, under the tre-

　　mendous pressure of the crust and

　　(10) 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

　　(15) cooler material to the depths. When

　　the edge of one plate bends under

　　another and its cooler material is con-

　　sumed in the mantle, volcanic activity

　　occurs as molten lava rises from the

　　(20) downgoing plate and erupts through the

　　overlying one.地球板块运动及火山爆发产生

　　Most volcanoes occur at plate

　　boundaries. However, certain “mis-

　　placed” volcanoes far from plate

　　(25) edges result from a second, indepen-

　　dent mechanism that cools the deep

　　interior of Earth. Because of its prox-

　　imity to Earth’s core, the rock at the

　　base of the mantle is much hotter than

　　(30) rock in the upper mantle. The hotter the

　　mantle rock is, the less it resists flow-

　　ing. Reservoirs of this hot rock collect

　　in the base of the mantle. When a

　　reservoir is sufficiently large, a sphere

　　(35) 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

　　(40) 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

　　(45) 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

　　(50) 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. 不在边缘火山爆发原因解释

　　现象解释

　　逻辑简图：

　　1P: earth consists of… mantle’s motion analogous to boiling water. One plates bends under another, volcanic activity…

　　2P: most occur at boundaries. However, certain occur far from edge result from……. The natural history of H shows….

　　以上就是本期GMAT试题的所有内容，考生可以此为据并进行针对性的练习，逐步掌握GMAT阅读的解题规律及技巧，以达到迅速提高GMAT考试成绩的目的。 相关链接：

1.GMAT考试资料：GWD试题合集（十六）

2.GMAT考试资料：GWD试题合集（十五）

3.GMAT考试资料：GWD试题合集（十四）

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