A parent group is discussing different types of punishment. The parents ask the nurse to discuss corporeal punishment. What would be the nurse’s response

A. "Corporeal punishment does not physically harm the child. "
B. "Corporeal punishment can result in children becoming accustomed to spanking. "
C. "Corporeal punishment can be beneficial in teaching children what they should do. "
D. "Corporeal punishment reinforces the idea that violence is not acceptable. "

木块A、B分别重50 N和60 N，它们与水平地面之间的动摩擦因数均为0.25．夹在A、B之间的轻弹簧被压缩了2 cm，弹簧的劲度系数为400 N/m．系统置于水平地面上静止不动．现用F="1" N的水平拉力作用在木块B上，如图所示．力F作用后：(      )

A．木块A所受摩擦力大小是12.5 N

B．木块A所受摩擦力大小是7 N

C．木块B所受摩擦力大小是15 N

D．木块B所受摩擦力大小是9 N