看看这句语法 时态有没有问题

题目

看看这句语法 时态有没有问题
When the prey had discovered the puma,it had been already attacked by t
改为 When the prey discovered the puma,it had been already attacked by the puma.呢

答案

你这里的时态很乱
When the prey was discovering the puma,it had been already attacked by the puma.
当猎物发现猎豹时,它已经被猎豹攻击了
表明 主句的动作早于从句的动作