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？

讲解

DS：已知9个数的平均数是43，求标准方差 1）最小的那个数是43 2）最大的那个数是43

一个数n的因子有2，3，5，n < 200，求n？ 条件1：4不是他的因子 条件2：9是他的因子

一辆火车走600 miles的路程，一般需要10h；火车中间走了一段速度20 miles的路；接下来是速度60miles的路，问速度60miles走了多久？ 条件1：速度20 miles走了3个小时 条件2：600 miles路程平均速度为56miles

一个数被10r整除，但不被10r+1整除，求r？ 条件1：这个数被25整除不被26整除 条件2：这个数被56整除不被57整除

数学考了一道，本来某一天下午两点水池剩n方水，每小时漏1/4方，每天下午一点会加进去14方，问水池剩m方的时候是星期几几点？

一个长方形长x宽y，能不能比较沿x边卷起的圆柱体体积和y边卷起圆柱体的体积？ 条件1：2x大于y 条件2：x小于3y

一个公司准备给一个地区中大于等于65，并且在当地呆的时间小于等于5年的人，发放谋谋福利，问这部分所占比例？ 条件1：该地区≥65岁的占比（某个值） 条件2：该地区呆的时间≤5年的人占比（某个值）

问x^y是否是odd？ 条件1：x是odd 条件2：可以求出来y是odd

编号1-8的蓝木板放到一个箱子里，编号1-8的红木板放到另一个。每个箱子各抽一块板，问抽到蓝木板和红木板编号一样的几率是多少？ 老师为什么不是 1/64?