英语得现在完成时什么时候用延续性动词

有一段时间时用延续性动词
比如说 我呆在家3个小时了
Ihave stayed at home for three hours
没有一段时间时
不用延续性动词
比如我买了这只笔
I have bought this pen
当然这句话换成延续性动词可以改成
我拥有这只笔 3天了
I have had this pen for three days
Are you clear?