A. 限制集电极电流的大小 B. 将输出电流的变化量转化为输出电压的变化量 C. 防止信号源被短路 D. 保护直流电压源EC
A. 对 B. 错
A. shall be B. be C. were D. is
A. know B. knew C. will know D. have known