增量式光电编码器用于精度要求不高的测量时要选用旋转一周对应（）器件。
A、电流较大
B、电压较高
C、脉冲数较多
D、脉冲数较少
参考答案：D
His generosity _______ him the reputation of “The most generous man” in his area.
A．made
B．earned
C．achieved
D．gave
何谓三次灾害？
