根据刀面与砧板接触的（）来划分，刀法分为三种。
A、面积
B、大小
C、角度
D、方向
参考答案：C
American English has changed _____ the centuries. There are several reasons _____ this. [ ]
A. over; for
B. for; with
C. in; of
D. during; about
多数认为诊断用超声在多少声功率时对人体无损害
A．0.1W/cm2以下B．0.1W/cm2以上C．0.2W/cm2以下D．0.2W/cm2以上E．0.3W/cm2以下
