第31题: [单项选择]回归与相关分析中,若两变量x,y的相关系数近似为0,以下推断错误的一项是 A. 与常数项的大小无关 B. 如果充分增加样本量,也能否定 H0:ρ=0 C. x与y可能有非直线的相关关系 D. x与y的关系用直线方程表达的意义不大 E. 回归系数也近似为0 参考答案:E 答案解析:相关系数近似为0,不一定回归系数也近似为0,因为回归系数还要受到变量单位的影响。
A. they had chronic anemia caused from poor diet B. they had many children C. they had to work for twenty-two dallors a week D. they had no one to take good care of their children 参考答案:A 答案解析:[关键词语]anemia,poor diet [详细解答]A他们因饮食差患有慢性贫血症。此句紧接着主题句而出。故选A;B他们有许多孩子。文中虽有提及,但并未说这是疲劳的原因;C他们得为了二十二美