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？

The profit from the sale of a certain appliance increases, though not proportionally, with the number of units sold. Did the profit exceed $4 million on sales of 380,000 units? (1)The profit exceeded $2 million on sales of 200,000 units. (2)The profit exceeded $5 million on sales of 350,000 units. 1不够，2 怎么看？ 谢谢

A report consisting of 2,600 words is divided into 23 paragraphs. A 2-paragraph preface is then added to the report. Is the average (arithmetic mean) number of words per paragraph for all 25 paragraphs less than 120 ? (1) Each paragraph of the preface has more than 100 words. (2) Each paragraph of the preface has fewer than 150 words.

PS ：给树标号，范围是201到740 某一品种的树的百位一定是4、5、6、7，个位一定是2、3、4、5， 求随便抽一棵树不是这个特定品种的树的概率？

DS：is|x-y|>|x-z|？ 条件1：是y的绝对值大于z的绝对值 。 条件2：是x<0。

1 3 2 B 3 4 4 10 A 2 8 1 第一列是调查的信用卡的拥有数，第二列是对应的人数，如第一行的意思就是三个人每人拥有一张信用卡，问信用卡拥有数的中位数？ （1）A=6 （2）B=7

m*(m+5)*(m+6)的因数可能是哪几个？ 3 ， 4 ， 6

连续四天股票收盘分别停在了8230，8390，8460，8530（数字可能有出入），第五天收盘多少？ （1）这组数的差值是220 （2）8390是这组数的中位数

三角形ABC，点D在AC上，D不能与AC相交（解释说这句话的意思是BD不能等于BA和BC，是独立的），AB是否等于BC？ （1）角BDC=角BCD （2）BD=DC

有A和B，共n个人（人数已知）他们每个人都可以同意或不同意一件事情，已知A有X人，B有Y人，bothA和B有Z人，求又是B又不同意的人？

给了两种书数量的比例3：X，求X？ （1）数的总数是15 （2）X小于13 讨论说选A，因为比例不能是3:12，必须要是最简形式1：4，可是我觉得3:12可以，3:2也可以，条件1不充分