Definition
Referring to a period of time in the past.
当年
In those days, people used to communicate through handwritten letters.
在那些日子里，人们通常通过手写信件来交流。
In those days, children's entertainment was mostly outdoors.
在那些日子里，孩子们的娱乐大多是在户外。
Back in those days, I used to look forward to the time after school every day.
在那些日子里，我每天都很期待放学后的时间。