When people engage in activities that help others, their brain releases endorphins, the brain’s natural opiates, which induce in people a feeling of well-being. It has been suggested that regular release of endorphins increases people’s longevity. And a statistic on adults who regularly engage in volunteer work helping others shows that they live longer, on average, than adults who do not volunteer. However, that statistic would be what we would expect even if volunteering does not boost longevity, because___________ Which of the following most logically completes the argument? A In the communities studied, women were much more likely to do regular volunteer work than men were, and women tend to live longer than men do B The number of young adults who do regular volunteer work is on the increase C The feelings of well-being induced by endorphins can, at least for a time, mask the symptoms of various conditions and diseases, provided the symptoms are mild D It is rare for a person to keep up a regular schedule of volunteer work throughout his or her life E Some people find that keeping a commitment to do regular volunteer work becomes a source of stress in their lives 错选了C，答案给的A。A说女士比男士更可能做志愿活动，女士比男士活得长。这不是支持原文了么？可以题目不是应该驳斥吗？

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！