质量分布均匀的摆球质量为m，半径为r，带正电荷，用长为L的细线将摆球吊在悬点O作为单摆，则这个单摆的振动周期T=______；若在悬点O处固定另一个正电荷，如图所示，则其振动周期______（填“变大”、“变小”或“不变”）．

The couple don't generally give in to each other, so they ________ when they are together.[      ]

A. have quarreled  

B. are always quarreling

C. had quarreled  

D. have been quarreling