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[Issue Essay]

试题详情

题目:

Analytical!

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答案:

提问:

老师您好能否帮我讲解下下面这个文章考试时该如何读,我读完这种文章压根不知道在说什么,只知道在讲ocean basin形成机制的几种理论。No very satisfactory account of the mechanism that caused the formation of the ocean basins has yet been given. The traditional view supposes that the upper mantle of the earth behaves as a liquid when it is subjected to small forces for long periods and that differences in temperature under oceans and continents are sufficient to produce convection in the mantle of the earth with rising convection currents under the mid-ocean ridges and sinking currents under the continents. Theoretically, this convection would carry the continental plates along as though they were on a conveyor belt (conveyor belt: n. 传送带) and would provide the forces needed to produce the split that occurs along the ridge. This view may be correct: it has the advantage that the currents are driven by temperature differences that themselves depend on the position of the continents. Such a back-coupling, in which the position of the moving plate has an impact on the forces that move it, could produce complicated and varying motions. On the other hand, the theory is implausible because convection does not normally occur along lines, and it certainly does not occur along lines broken by frequent offsets (an abrupt bend in an object by which one part is turned aside out of line) or changes in direction, as the ridge is. Also it is difficult to see how the theory applies to the plate between the Mid-Atlantic Ridge and the ridge in the Indian Ocean. This plate is growing on both sides, and since there is no intermediate trench, the two ridges must be moving apart. It would be odd if the rising convection currents kept exact pace with them. An alternative theory is that the sinking part of the plate, which is denser than the hotter surrounding mantle, pulls the rest of the plate after it. Again it is difficult to see how this applies to the ridge in the South Atlantic, where neither the African nor the American plate has a sinking part. Another possibility is that the sinking plate cools the neighboring mantle and produces convection currents that move the plates. This last theory is attractive because it gives some hope of explaining the enclosed seas, such as the Sea of Japan. These seas have a typical oceanic floor, except that the floor is overlaid by several kilometers of sediment. Their floors have probably been sinking for long periods. It seems possible that a sinking current of cooled mantle material on the upper side of the plate might be the cause of such deep basins. The enclosed seas are an important feature of the earth’s surface, and seriously require explanation because, in addition to the enclosed seas that are developing at present behind island arcs, there are a number of older ones of possibly similar origin, such as the Gulf of Mexico, the Black Sea, and perhaps the North Sea.

解答:

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阅读269878
解答: 郭培月

提问:

圈出来的部分,说是用that不用which,但是没明白为什么

解答:

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阅读249193
解答: 金栩竹老师

提问:

曼哈顿里的例句 A hard worker and loyal team player, the new project was managed by Sue. 书上说的是前面的modifier会错误修饰project,但平时阅读的时候读到这个是能够判断这个修饰语是不会用来修饰project的,会对阅读产生阻碍但不会令人误解。因此想问Gmat语法中这种例子是绝对不对还是不优呢。

解答:

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阅读249855
解答: 金栩竹老师

提问:

还请MAY老师帮忙解答下这道题,我选的B,没弄明白,谢谢

解答:

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阅读249685
解答: ken@boost.org.cn老师

提问:

请问数学老师 为什么这个题不是0.8*0.4+0.2*0.6。因为两个不同时发生啊

解答:

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阅读248753
解答: ken@boost.org.cn老师

提问:

请问数学老师 这个题为什么不能直接是九分之二

解答:

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阅读248604
解答: ken@boost.org.cn老师

提问:

请数学老师解答。这个题您没答完吗?这是系统出问题了吗?

解答:

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阅读247305
解答: ken@boost.org.cn老师

提问:

请数学老师解答条件2为什么可以

解答:

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阅读246206
解答: ken@boost.org.cn老师

提问:

请数学老师讲解 条件1为什么可行 谢谢

解答:

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阅读245862
解答: ken@boost.org.cn老师

提问:

请数学老师讲解思路 谢谢

解答:

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阅读245862
解答: ken@boost.org.cn老师

提问:

请数学老师讲下思路,这个题我始终都无法算出正确结果

解答:

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阅读242825
解答: ken@boost.org.cn老师

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