提问： 王文静老师，我想问个关于',＋doing'和and的问题，下面整理的问题，我都是在这个地方出现犹豫或者选错,真的是屡做屡错，字有点多，麻烦老师看下啦 Q849是一个句子＋doing的结构，letting引导的是一个对前面动作进行补充解释的动作，与前面的句子是有关系的，所以不能用and去连接，因为and连的是相互独立的没有关系的动作或者事情 Q851 gives mouth和displace grasses并列，造成的结果用rendering作为引导跟在后面，也算是补充解释 Q862也是句子＋,＋doing作为前面一整个句子的补充解释 但是问题来了，Q858 B选项，south are hunting crops and therefore raising这个为什么能对? and不是连接相互独立的两个部分吗，那therefore就是表示因果关系的啊，这不是矛盾了吗，还是这道题目主要的考点不在这里而在于平行，所以有瑕疵也是可以容忍的? Q 865虽然正确选项B可以通过其他考点排除，但是'overcompensating，growing'为啥不好呢，growing an extra one or two不能作overcompensating的补充解释吗，这里有必须选and不选doing,doing的理由吗？

请问老师这道鸡精题解题思路

我想问第49题，第二个条件，由公示得出f（a）*f（b）=10a方✖️10b方=100a方✖️b方，所以只能a方✖️b方为0，所以结果为0？

文章：According to many analysts, labor-management relations in the United States are undergoing a fundamental change: traditional adversarialism is giving way to a new cooperative relationship between the two sides and even to concessions from labor. These analysts say the twin shocks of nonunion competition in this country and low-cost, high-quality imports from abroad are forcing unions to look more favorably at a variety of management demands: the need for wage restraint and reduced benefits as well as the abolition of "rigid" work rules, seniority rights, and job classifications. Sophisticated proponents of these new developments cast their observations in a prolabor light. n return for their concessions, they point out, some unions have bargained for profit sharing, retraining rights, and job--security guarantees. Unions can also trade concessions for more say on the shop floor, where techniques such as quality circles and quality-of-work­ life programs promise workers greater control over their own jobs. Unions may even win a voice in investment and pricing strategy, plant location, and other major corporate policy decisions previously reserved to management. Opponents of these concessions from labor argue that such concessions do not save jobs, but either prolong the agony of dying plants or finance the plant relocations that employers had intended anyway. Companies make investment decisions to fit their strategic plans and their profit objectives, opponents point out, and labor costs are usually just a small factor in the equation. Moreover, unrestrained by either loyalty to their work force or political or legislative constraints on their mobility, the companies eventually cut and run, concessions or no concessions. Wage-related concessions have come under particular attack, since opponents believe that high union wages underlay much of the success of United States industry in this century. They point out that a long-standing principle, shared by both management and labor, has been that workers should earn wages that give them the income they need to buy what they make. Moreover, high wages have given workers the buying power to propel the economy forward. f proposals for pay cuts, two-tier wage systems, and subminimum wages for young workers continue to gain credence, opponents believe the U.S. social structure will move toward that of a less-developed nation: a small group of wealthy investors, a sizable but still minority bloc of elite professionals and highly skilled employees, and a huge mass of marginal workers and unskilled laborers. Further, they argue that if unions willingly engage in concession bargaining on the false grounds that labor costs are the source of a company's problems, unions will find themselves competing with Third World pay levels-a competition they cannot win. 想请问郭老师，这题opponents观点是在第三段，但是原文和选项要怎么对照呢...怎么从观点看出态度？

请问may老师 13) In triangle ABC, point X  is the midpoint of side AC  and point Y  is the midpoint of side BC . If point R  is the midpoint of line segment XC  and if point S  is the midpoint of line segment YC , what is the area of triangular region RCS  ? (1)   The area of triangular region ABX  is 32. (2)   The length of one of the altitudes of triangle ABC  is 8. 答案；A

求问此题：(3!+4!+5!)/(4!+5!+6!) =?

２１）Is │x - y│>│x - z│?（绝对值比大小思路？） (1)   │y│>│z│ (2)     x < 0 E 请问may老师

DS：求1/a+3/b等于多少？ 条件1：a和b的最大公因数是6 条件2：a和b的最小公倍数是120

请问老师，这题选项应该是A吧？谢谢！

一个立方体塑料盒内腔长宽高分别是x、y、zcm，塑料厚度是1，问塑料体积。谢谢老师解答！

求问此题：DS：K为正整数，问是否有超过3个的prime factor？ 条件1：K>30 条件2：K<20 很多人选A；我觉得应该选D;∵Prime Factors有：2/3/5/7……把最小的不同质数相乘=2*3*5=30；那么由条件一可得：K必然有超过三个以上的prime factors；有条件二可得K的不同质数必然只有2和3.所以俩条件都充分，请老师解答。谢谢！