当钢板弹簧的垂直刚度不变时，增加主片长度对于弹簧纵向角刚度值大小影响是（）。
A.无法确定
B.保持不变
C.变小
D.变大
参考答案：D
Although your son made some mistakes, he worked hard at his lessons. You shouldn't be hard ______ him. [ ]
A. in
B. at
C. on
D. for
目前，我国各家银行多采用逐笔计息计算( )利息。
A．活期存款B．整存整取存款C．定活两便储蓄存款D．个人通知存款
