had done 是过去完成时，它使用的语境是一个动作或状态发生或存在于过去某个动作或时间之前。简称“过去的过去”。如：Tom told me he had learned the news. 再如：I had finished my report two days before. 而 has done 表示过去发生的动作延续到现在或对现在有影响。简言之与现在相关。如: She has lived here for five years.
Had done和has done是两种时态的谓语部分构成。Had done是过去完成时，过去完成时表示相对于过去的某一个时间而言，动作已经完成，表达的意思是过去的过去。例如，he had done the work When i came in。
Has done是现在完成时表示相对于现在而言，动作已经完成。例如，he has done his homework，he can watch TV。
