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.

这个是怎么算的，我只能看出要求的人数是总人数的百分之三

这题除了试数还有什么好方法吗？如果试数的话，如何快速找到适合的数呢？

条件二说的是每一项Sn都大于5吗？，但是n/（n+1）不是小于1吗？我不知道该怎么理解和使用该条件

条件2是要把对角线为8时的情况算出来吗？如果不是，应该怎么判断吗？另外五边形的面积应该怎么算呢？

这题怎么思考？还有绝对值不等式的考点有哪些啊

B单独不能成立吗？k=7带入不等式中，不是可以限制m和n的范围吗

题干不是已经能排出+和➗好了吗？因为此时式子没有意义。那两个条件为什么不能单独成立呢？这题的逻辑是什么

条件2为什么单独不成立？B做了超过50%，说明B比A效率高，那么3小时内可以完成

已知由一个符号@表示的加减乘除中的一一个符号。如果a@ (-a) =0,那么a=0.问:以下条件能否判断符号@是加减乘除中的哪一个?条件1).其中a@(a@a)=0, a=0;条件2).其中a@(b@c)=(a@b)@c. 答案：E

老师这道题和后面你讲的6和4的例子没看懂！