备课是指制订学期教学计划、单元授课计划与课时教学计划。
参考答案：对
The equipment must be bought from a supplier _____ by the company. [ ]
A. being approved
B. to be approved
C. approving
D. approved
基站内交流配电箱、开关电源内的交流配电单元的SPD防雷保护等级是（）
A.A级、B级
B.A级、C级
C.B级、C级
D.B级、D级
