remember to do 表示記得去做某事 (未做)
remember doing 表示記得做過某事 (已做)
Remember to go to the post office after school.
記著放學後去趟郵局。
Don't you remember seeing the man before?
妳不記得以前見過那個人嗎?
類似的還有：
forget to do 忘記要去做某事。 (未做)
forget doing 忘記做過某事。 (已做)
The light in the office is stil on. He forgot to turn it off.
辦公室的燈還在亮著，它忘記關了。(沒有做關燈的動作)
He forgot turning the light off.
他忘記他已經關了燈了。 ( 已做過關燈的動作)
Don't forget to come tomorrow.
別忘了明天來。 (to come動作未做)
典型例題
---- The light in the office is still on.
---- Oh，I forgot___.
A. turning it off B. turn it off C. to turn it off D. having turned it off
答案：C。由the light is still on 可知燈亮著，即關燈的動作沒有發生，因此用forget to do sth.
而forget doing sth表示燈已經關上了，而自己忘記了這壹事實。此處不符合題意。
regret to do 對要做的事遺憾。 (未做)
regret doing 對做過的事遺憾、後悔。 (已做)
I regret to have to do this, but I have no choice.
我很遺憾必須這樣去做，我實在沒有辦法。
I don't regret telling her what I thought.
我不為告訴她我的想法而後悔。
典型例題
---You were brave enough to raise objections at the meeting.
---Well, now I regret ___ that.
A. to do B. to be doing C. to have done D. having done
答案：D。regret having done sth. 對已發生的事感到遺憾。regret to do sth. 對將要做的事感到遺憾。本題為對已說的話感到後悔，因此選D。