220kV系统，相间的最大操作过电压（标幺值）应为下列哪项数值？（）
A.3.0
B.3.2
C.4.0
D.4.8
参考答案：A
Mother wanted to be a good provider, a role she ________ since her marriage to
Father.
A．shoulders
B．shouldered
C．is shouldering
D．has been shouldering
Linux没有扩展分区。（）
