C1 时期；时代
a period in history
How did people communicate in the days before email? 没有电子邮件的时候人们是怎样交流的？
These were the days before antibiotics, when illnesses like that would kill you.
This is how people managed in the days before air-conditioning was invented.
The days of cheap petrol are behind us.
Thankfully, things have changed since the days of corsets and petticoats.
See also: day