Student or Learner
I have been learning English since three years ago.
Would you kindly let me know if the above sentence is grammatically acceptable ?
I am very grateful to you,Harry Smith, for your kind reply.
I think the reason is that an adverbial phrase,"three years ago" can not be an object of the preposition,"since".
Am I right ?
'Since 31 March 1998' = 'Since the day we first met' = 'Since our first meeting on 31 March 1998".
In some contexts, when the event is omitted and the date remains, this allows wrong-looking expressions like 'since three years ago":
This has been illegal since [the change in the law] three years ago.
As Casiopea wrote:
Use since + (a specific time) like March 31, or 9:19 a.m., or Tuesday.
Use for + (a length of time) like 1 day, or 3 hours, or 5 years.
You sentence, "...have been learning" is a form of the Present Perfect, which refers to a period of time, not a point in time. You can see from what Casiopea wrote, 'since' refers to a starting point in time, and it is 'for' which refers to a period/length of time.