不是说现在完成时和过去完成时要用延续性动词,只是说如果涉及到到时间段,那么只能用延续性动词。看下面俩个句子:I saw a pen in the shop . And I have already bought it.(无表示时间段的状语,因此可用Bought这个短暂性动词)I have had the pen for a week.(这句话意思可以理解为“这支笔我买了一周了”,for a week就是时间段,那么此句中的谓语动词则必须用延续性动词)