影响评价的因素（）
A.时间因素
B.回归因素
C.测量工具因素
D.选择偏倚
E.失访
参考答案：A, B, C, D, E
举例说明金属活动性顺序有哪些不同的应用？（化学反应要用化学方程式来表示）
A laborer is paid $8 per hour for an 8-hour day and
times that rate for each hour in excess of 8 hours in a singe day. If the laborer received $ 80 for a single day’s work, how long did he work on that day
times that rate for each hour in excess of 8 hours in a singe day. If the laborer received $ 80 for a single day’s work, how long did he work on that day