提高单级放大电路的电压放大倍数有效途径是（）
A.增大三极管β值
B.增大集电极电阻RC
C.提高静态发射极电流
D.增大偏流电阻Rb
参考答案：C
--What did the professor ask us to do just now?
--Sorry, I ______ about my trip to the Wolf Hill at the weekend.
A．had thought
B．was thinking
C．thought
D．think
宣传
