a / per day

< Previous | Next >


Senior Member
Hi everyone,
recently I'm being puzzled by how and when to use a/per day (month, year...). I know some expressions that are correct but never had learned any rule so sometimes I'm confused while speaking.

Can anyone explain me wheteher and what the rule is? I'll be more than happy :)

My sentences that I know (I believe) are correct:
- Take these pills twice a day.
- I usually work 8 hours per day.
- He vists his uncle no more than 4 times a month.
- We have 10 days off per month.
  • < Previous | Next >