为了提高MOS电路的带载能力,常采用一种称为()的电路作为MOS电路的输出级。
A.双调谐
B.变压器
C.三态驱动器
D.放大器
参考答案:C
Her________to become a teacher was held back by her poor spoken English.
A.instruction
B.situation
C.ambition
D.condition
若一元二次方程x2+2x+k=0有两个实数根,则k的取值范围是( )。