after+点时间：He came home after 10 o'clock last night.
after + 一段时间(这里的时间段一般不是具体时间,如,一般不说after three days ,,而是three days after.,但可以说 after a period of time ) ,如：
They had known the news three days after.
After a period of time / After a while,he returned.
时态的用法区别也应该明了吧!