功放电路的效率主要与______有关。
A．电路的工作状态 B．电路输出的最大功率C．电源提供的直流功率 D．以上都不对
参考答案：A
The doctor recommended that you swim after eating a large meal.
A wouldn't B couldn't C needn't D shouldn't
PDCA的特点不包括( )。
A．完整循环 B．逐步上升的循环 C．大环套小环 D．无止境的循环
