如果交流电的频率是50Hz，则该电流的方向每秒改变1∞次。
参考答案：对
--Can I call you back at two o’clock this afternoon?
---- I’m sorry , but then I ______ to Beijing . How about five ?
A．fly
B．will be flying
C．will fly
D．am flying
如何注重对员工的培养发展？
