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.

These days, publishers in Ramistan of glossy Western-style magazines rarely need to worry about interference from the government — the magazines’ content promotes consumption, and convincing Ramistan’s emerging middle class to spend their money is a key component of domestic policy. 想问选项A的and convincing是修饰谁的呢？修饰content的话为什么可以在前面加and？ 选项C为什么语法不正确呢？

plums are 75% water. prunes are 15% water. how much water must be evaporated for x kg of prunes? 这是我今天考场上的题，好像做错了。我乱选了（85x/15） 其他选项有各种 25x/85，15x/75什么的。应该怎么做？

一辆车，车轮上有一点离圆心 d cm，车子前进 D cm，问该点距离/车子前进的距离？ 1. d等于一个值 2. D等于一个值

Shoppers at Retailer R who purchased substitute items from other manufacturers on DayI paid a total amount that was approximately 78 of the total shoppers would have paid had each of them been able to purchase ProductXon Day 1. “was 和 would have paid ”都在一个从句里，怎末会有两个谓语动词？“had each of them been able to...”这部分是跟谁啊？看不懂

On his drive to work, Leo listens to one of three radio stations, A, B, or C. He first turns to A. If A is playing a song he likes, he listens to it; if not, he turns to B. If B is playing a song he likes, he listens to it; if not, he turns to C. If C is playing a song he likes, he listens to it; if not, he turns off the radio. For each station, the probability is 0.30 that at any given moment the station is playing a song Leo likes. On his drive to work, what is the probability that Leo will hear a song he likes? 这个题目的0.3为什末代指在A station 播放到了自己喜欢的？不太理解0.3到底指的是甚麽

提问叶老师，这个题我不太理解为什么appear要用单数？ D选项，what 指什么？from what 这个倒装正常语序应该怎么写？

等腰直角三角形的周长为：16+16√2 ；问斜边的长度 等腰直角三角形的非直角边一样长：那设为x 所以斜边就为（根据勾股定理）x√2 所以周长：x+x+√2 x=16+16√2 2x+√2 x=16+16√2 X=8√2 斜边就等于：16 问题：X=8√2 是怎么算出来的？

为什么算到这一步(3^2-2^2)(3^2+2^2)(3^4+2^4)就能直接算答案了（答案:5x13x97），难道有4次方的地方不继续化简吗？我怎么知道要把公式简化到哪一步？

老师好 我这道题的方法就是解二次方程，只有唯一正解才能证明是充分的。（我发现很多应用题都是这样）但是我发现解二次方程很浪费时间，考试的时候可能没那么充分的时间，怎么办呢？这道题还有更好的方法吗？谢谢老师