in +时间段:与将来时连用
after +时间段:与过去时连用
after +时间点:可与将来时连用
He will be back in two hours.
He came back after two hours.
He will be back after two o'clock.
in +时间段:与将来时连用
after +时间段:与过去时连用
after +时间点:可与将来时连用
He will be back in two hours.
He came back after two hours.
He will be back after two o'clock.