在晶体管放大电路中，如果反馈信号取自输出电压，称为（）。
参考答案：电压反馈
Your friend _____ doesn't work hard asks you to help him cheat in the exam by looking at your paper.
A. who
B. whom
C. which
D. whether
DIC早期应选用
A．肝素
B．华法林
C．链激酶
D．右旋糖酐
E．以上都不是
