in年in月in季节，如“in 2020”在2020年；in早中晚在本周，如 “in the morning ”；具体到日就用on，如“ we are going to travel on march 1st”；at加准确点与分，如“at five aclock”.

相关介绍

at

prep.在(某处);在(学习或工作地点);在(某时间或时刻)

English is a compulsory subject at this level.

英语在这一级别是必修科目。

Interest is charged at a flat rate of 11%.

利息按标准比率11%收取。

We left at first light.

我们黎明时离去。

She was still half asleep when she arrived at work.

她到了上班地点时仍然睡眼惺忪。