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.

语法题目，请指定王文静老师回答。 问题语法讲义-修饰-第十题-Psychiatrist题目，我感觉选项A.B都是一样的意思，而且2个选项都没有问题，不知道该如何取舍。谢谢

老师，这道题怎么解的？我自己的理解是，速度慢的机器有1到3台，把每台多出来的1小时加在一起除4，求得的平均值就是小数点后的数字。所以求的平均值最小是0.25不可能是0.2因此选项A，7.2是不可能的。但是不知道这道题是不是这么理解的。

老师，这题答案是D，但我觉得是C。题中说大于10小于100的整数，应该是89个，掉到过来98+9，个位数是7

20题我计算是95页，但是答案是B，99页，不知道怎么算出来的。

老师25题答案给的是30%.可是我怎么算都应该是40%呢？我算错了吗？应该怎么算？

老师这道题没明白是什么意思

老师，第12题我没明白是什么意思

这个是Tina 老师在语法课上讲的一道题，不知道为什么搜不出来。想问一下，正确答案B 选项中的begun为什么不是过去分词引导的状语从句修饰the autographed quilt? Tina 老师在课上讲的是：begun是就近修饰名词fad的，我就很迷茫。我一直记得您讲过过去分词和现在分词作状语是修饰不到SVO 的O 上的，那这个为什么例外呢?谢谢您!

One day 340 million shares of stocks were sold. Among them 3/4 are domestic stocks. Among all the stocks sold 3/5 belong to institutional transactions. What is the minimum number of domestic shares could be traded by private parties on that day? 想问下这道题怎么画图解决？

请陆旭老师回答第25题，没有思路