场输出级采用双电源供电的原因是（）。
A.提高效率
B.缩短场逆程时间
C.A和B
D.减小非线性失真
参考答案：C
An analyst gathers the following information about a company and the company’s industry:
The company’s operating cycle: （）
A. and cash conversion cycle are both longer.
B. is longer, but the cash conversion cycle is shorter.
C. is shorter, but the cash conversion cycle is longer.
按照所要求的质量指标从原料煤中分选出合格产品的难易程度叫煤的（）。
