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？

@Tina老师，老师，这道题帮忙讲一下b和c选项呗。主要区别在谓语单复数和后面的to provide 还是providing。主语是两个不可数名词and并列，谓语要用复数么？

@陆旭老师 我想问一下 这里面的数字7是哪里来的呀？我想了一下排除0和它本身应该还有8个呀，不是很明白。

@陆旭老师 为什么这道题选b呀？我把（1）代进去能求出答案，把（2）代入则x=5与题目要求不符，求讲解。谢谢

@陆旭老师 这道题思路是什么呀？应该怎么做呢？

这道数学题 我想问问数学老师为什么我的两个方法答案都不对 首先 我理解这道题是问事件M或者R只发生一个的概率 我的第一个方法就是用M发生*R不发生+M不发生*R发生 这样哪里出错了 需要怎么改呢？ 我的第二个方法是用总体减去M和R同时发生的概率再减去M和R都不发生的概率，这里哪里出错了 要怎么改呢？ 谢谢老师的回答！

@英吉老师 我想问一下这道题A选项错在了哪里，算是犯了什么错误？

@英吉老师 这一道题里的c选项还是不是很明白哪里错了，请问这句话要是怎么改就算对了呢？

@徐小梅老师，徐老师您好，第4)题，我也看到了“至少2人”这个字眼，也是按照至少2人来算的。但我是这么理解的：原来男女共有12个人，先从5个女生中取2个人，保证了至少有两个女生，所以是C5^2; 接着，再让剩下的3个女生和7个男生合并，共10人，取3个人（此时不论男女都可以），是C10^3。然后合起来就是C5^2*C10^3。

为什么4）不能直接用C5^2 *C10^3?先从5个女生中选2人，再从剩下的10人中选3。这样我算出来的是1200。但是按照图片上老师的方法算的是596。很疑惑，求老师解答一下，谢谢！

为什么分子是5 就一定有一个分母是2的三次方有一个分子是1呢？