ZPW-2000A无绝缘移频自动闭塞系统发送器故障表示灯每周期闪动4次，说明（）故障。

A、功出电压检测故障

B、下边频检测故障

C、上边频检测故障

D、型号选择条件故障

All of followings should be done by the project manager during project control except ______.

A. Determine the a change has occurred
B. Ensure that a change is agreed
C. Make sure all changes are approved by management
D. Manage changes as they occur