GWD 7 23

wupa

没有人问过这道题，不过还是有疑问

答案选的是B

我选的是A

我觉得不应该是B，因为稳中没有提到过“differ from each other in age”

而A，文中踢过“a track marking the position of the plume relative to the moving plate” line 50

不知道大家觉得呢

GWD7-Q22 to Q25:

      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.

             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.

--------------------------------------------------------------------------------

Q23:

It can be inferred from the passage that a chain of volcanoes created by a mantle plume would most likely be characterized by

             

1. a curved outline

2. constituent volcanoes that differ from each other in age

3. occurrence near a plate boundary where one plate bends under another

4. appearance near many other volcanic chains

5. rocks with a wide range of chemical composition

复活节快乐

是Ｂ啦，即然是叫你推断的怎么可能在文中明确指出呢！这种火山的存在很好的证实了大陆漂移说，上层陆地在动，而下面火山的源头在深处是不随大陆移动的，但是岩浆要寻找出口喷发，那就会在地表出现volcanic chains，chain中的每一个火山口形成的年代肯定是不同的．但没说过chain一定是直线还是曲线，因为这是大陆漂移的方向决定的．

wupa

可是如果从ets的出题思路中来说

答案必然是要文中有明确指出线索的

我还是觉得在不同的时期形成这个没有在文中指出阿

而curved 是根据那个a track 判断出来的。。。。

可能我又钻牛角尖了。。。

nancyx83

请问楼主你的GWD是从哪里下载的？可不可以告诉我个链接？我下载的和你的不一样，不知道怎么回事。