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？

调查1200人对A B C 的喜好，喜欢A的40%，喜欢B的58%，喜欢C的40%，同时喜欢AB的30%，求喜欢C但不喜欢A B的人

问题：在“数的整除性质小节中”，第一段写到，如果a能被b整除，记作aΙb. 但如果照这么理解的话，为什么在性质3: 如果b、c都能整除a且b和c互质，那么b与c的积能整除a。以上说法化成公式的表示为：bΙa 。但如果根据上面的被整除表达，这里不应该写为aΙb嘛？

G（x）表示x的取整且是小于x的，L（x）表示x取整且是大于x的，问L（x）-G（x）的所有可能值的的集合？ （-1,0） （1,0）等

题目：1993年的元旦是星期五，1994年的元旦是星期几。 问题：在文字解释中提到，问题的实质是求用7去除某一天的天数后所得的余数。然后引出，因为15与365除以7后，余数都是1，所以15与365对于模7同余。但15这个数字是怎么推到出来的呢？

问题：由于以前完全没有学习过“同余”的概念，因此书中的解释完全不明白。还烦请MAY老师帮忙讲解一下。

题目：求143∧89（143的89次方）除以7的余数 问题：（1）如何利用同余的概念推出最后的结果的？ （2） 如果可以不用同余概念，还有什么其他方法可以处理此类题型嘛？

题目：A Printer numbered consecutively the pages of a book, beginning with 1 on the first page. In numbering the pages, he printed a total of 189 digits. How many pages are there in the book? 问题：看了中文翻译并听了管老师的讲解，我都没弄明白这个题目的解题思路。的别是对“a total of 189 digits”的处理。

DS：已知半径为7，求ABR 的周长？ 条件1：∠x=120 度 条件2：△ABR 的面积为(49/9) π 图片附件

题目：If n is a prime number greater than 3, what is the remainder when n的平方is divided by 12? 问题：当管老师解题时，他出了3个方程式，分别是： 1） n=3A+1, n的平方=9A(square)+6A+1 2) n=3A+2, n的平方=9A(square)+12A+4 3) n=2A+1, n的平方=4A(square)+4A+1 我不明白的点是：这3个方程式是怎么推到或者是一看到题目就这么设出来的？

有图。