功率因数是指电动机从电网中吸取的有功功率和（）的比值。
A、视在功率
B、励磁电流
C、无功功率
D、谐波
参考答案：A
A project management team has subcontracted work to a service company. Which of the following tools is the best choice to assure that this company will be able to meet the quality requirements of the project
A) Quality audit. B) Deliverable inspection. C) Fixed price contract. D) Service level agreement.
信用风险带来损失的直接原因有（）。
A.交易对手直接违约
B.经济危机
C.市场利率波动
D.汇率波动
E.交易对手信用评级下降
