Hello all forum users!
The sell-by date has long expired.The sell-by date expired a long time ago.
The above-mentioned sentences were created by me, and in my opinion they mean exactly the same. The only difference is the use of tenses. "Long" tends to be used with the Present Perfect tense whereas "a long time ago" is usually employed with the Simple Past tense.
I would be grateful for putting me right on that.
'Long' means "for a long time". "I have long admired his talents". You can use that with the present perfect; it means for a long time up until now at least.