The British sociologist and activist Barbara Wootton once noted as a humorous example of income maldistribution that the elephant that gave rides to children at the Whipsnade Zoo was earning annually exactly what she then earned as director of adult education for London. (A) that the elephant that gave rides to children at the Whipsnade Zoo was earning (B) that the elephant, giving rides to children at the Whipsnade Zoo, had been earning (C) that there was an elephant giving rides to children at the Whipsnade Zoo, and it earned (D) the elephant that gave rides to children at the Whipsnade Zoo and was earning (E) the elephant giving rides to children at the Whipsnade Zoo and that it earned 请问这道题为什么选A不选B呢，B的时态为什么不对呢？我的理解是elephant earning是在what she then earned 之前发生的，所以就过去完成时~~~ | 
