If a cake expired and the expiry date was December 31st (I made it up), is it grammatically correct to say that the cake expired back on December 31st? And how about "the cake expired on December 31st"? If they are both grammatically correct, is there a difference in meaning? Thank you!
2 Answers
back is used for emphasis:
The ticket expired back on December 31st.
The ticket expired on December 31st.
Same meaning. The back is often just used for emphasis in speech.
Also, some amount of time has gone by. For example, a month, or weeks.
It's very common to say something like "back in 2010..." (we say in a year, not on) when referring to something that happened a long time ago. It is not just for emphasis - it sometimes helps to indicate before you begin to speak about a historical date that it is in the past because we say 'on' when referring to both future and past dates.
While some people might occasionally say "back on [a specific date]" it's far less common - in fact, I'm not sure I've ever heard it at all. Consider how most English speakers talk about dates. If it was May, we refer to the future month as "this June", because it is June this year. We would do the same if it was July and June had passed. The next month of June is "next June". And when someone says something like "this bread expired on 31st May" it would be doubly superfluous to add "back" because it is a given that you mean May this year (not "back" in some previous year) and you have the word "expired" indicating that this is the past.
backemphasises that it's a long time ago. You couldn't say back on december 31 on the first of january because it would be the day before.