在這句話裡面的第一句Do not stay in the past 中，為什麼用in？,不能用on呢？在常用時間介詞中，in,on,at,for都是怎麼用的呢？

at：在某個時間點,比如：at six o’clock.

in：（1）用在一段時間前，如：星期，月，季節，年；（2）泛指的“在上午/下午/晚上”即in the morning/afternoon/evening.但是泛指的noon, night 前加at.

on：在具體某一天，或某天的上午，下午，晚上，比如：on Monday morning/afternoon/evening/night.

for: 表示時間段。表示“計；達”，比如：They will stay here for a month.

during: 時間段，“在……期間”,during the winter/ performance

after: “在……之後” After the earthquake, everything was out of order.

by: “到……為止，到……” We had finished our work by last Friday.

before: “在……之前” Wash your hands before dinner.

until/till: “在……以前”；“到……為止” We worked until darkness.

from...to: “從……到……” Weekdays are from Monday to Friday.

曾經像個寶寶

_in _ spring , __in_ the evening, _in__ the middle of May, _in__ 2014 ,

__in__ his thirties, _in_ five hours, __in__ January, __in__ the 1990's,

__in__ / during the day

總結1：在月，四季，年，年代，世紀，泛指的在上午/下午/晚上時間短語裡，以及其他表示較長時間的名詞短語前，用介詞in。

歡迎來到未來

_on_ Wednesday, _on_ Sundays, _on__ the morning of May 1st,

_on_ a cold night, _on_ a rainy afternoon, _on_ the fifth of July,

__on__ Christmas Day, __on__ Easter Day

總結2：在星期，具體某一天的上午/下午/晚上，以及節假日當天，用介詞on.

_at_3 pm, _at_night, _at__ that moment , _at__ present,_at_Christmas Eve,

at Christmas,_at__breakfast/lunch, _at__midnight, _at_ the age of 12, _at_the beginning of the year

總結3：用在時間點、中午(noon)晚上(night)固定搭配裡，以及節假日期間用介詞at.

Learn from yesterday, live for today, hope for tomorrow. 借鑒昨天，活在今天，憧憬明天。

I feel as if I had left school for a whole century. 我覺得我好像離開學校整整一個世紀了。

總結4："介詞for 表示時間的名詞短語" ，表示動作持續或狀态存在的時間段:。