总体回归函数中的随机误差项满足同方差性,即它们都有相同的方差。如果这一假定不满足,则称线性回归模型存在异方差性。()

A. 教学计划之外的活动
B. 教学计划之内的活动
C. 综合活动
D. 社会实践活动

A．.It’s fun, it works, it includes up-to-dated language and never forgets.
B．.It’s fun, it works, it mirrors culture, and not easy habit to learn English.
C．.It’s fun, it works, and too emotional.
D．.It’s fun, it enhances learning new information and an easy habit to do.