in, on, at 都是我们常用的时间介系词，如果你也常搞混的话，今天 VoiceTube 只要用三句话、不到十秒的时间就可以让大家马上搞懂这三者的差别，不相信吗？那就试试看啰！
好，in, on, at 用法的差别就在于：
at：一个准确、特定的时刻
in：月份、季节、年、世纪、一段长而非特定的时间
on：特定日期、星期
逻辑就只是这样而已！下面帮大家统整常用的时间用法，一起练习看看吧！
in + (months, years, centuries, long periods)
in the morning
in the afternoon
in the evening
in January
in February
in March, 2015
in the spring
in the summer
in the fall
in the winter
in 2015
in the past year
in the 18th century
in the week
in the past
in the future
on + (days and dates)
on Monday
on Tuesday morning
on Wednesday afternoon
on Thursday evening
on Friday night
on 28, April
on New Year’s Day
on Christmas Day
on the weekend
at + (precise time)
at 07:11
at 10 o’clock
at noon
at noon yesterday
at night
at midnight
at the same time
in the morning / at night
大家有没有发现一个问题？为什么我们用 in the morning, in the afternoon, in the evening, 但却是用 “at” night 呢？其实这个问题很多母语人士也无法真的说个明白，也有各种解释，但我把我偏好的一种解释跟大家分享：
如一开始所讲，in 用在一段较长而「非特定」的时间；at 用在一段「特定」的时刻，而 night 一般是英语人士表示睡前没事要做的那段「特定时间」，大概就是晚上九到十二点间，所以相较 morning、afternoon 这些范围较大且较无特定的时间，我们就相对会用 at night 喔！
还有几个特例值得注意一下，像 on the weekend 跟 at the weekend 都有人用，on Christmas 跟 at Christmas 也都有人用，使用上还是依习惯为主。
最后为了确认大家都了解，在下面有些小测验让大家练习，答案就在文章的最下面喔！
(1) Is Costco open ___ New Year’s Day?
(2) Jack often goes out ___ night.
(3) When I woke up ___ the morning, …
(4) I usually wake up ___ 9:00 ___ the morning.
(5) I suggest that he should come ___ Saturday morning.
(6) VoiceTube was founded ___ January, 2013.
Answers:
(1) on (2) at (3) in (4) at, in (5) on (6) in
