had done是过去完成时

had done是过去完成时，如果动作发生在相对于过去某一时刻的过去，在过去某时刻已经完成了，就用had done,例如“我昨天三点到家时，露西已经睡着了”对于过去某一时刻的昨天三点，已经睡着了，也就是露西睡着时比昨天三点还早，是昨天三点的过去，所以用Lucy had gone to sleep when I got home at three o'clock yesterday.

have/has done是现在完成时，是相对于现在动作已经完成了，have done主语是第一人称和第二人称和第三人称复数，has done主语是第三人称单数。例 现在我已经吃晚饭了I have already eaten my meal now.