[General] A year ago VS The year ago

[Iamdrachen]

Hello
Currently, I have practiced the error exams.
and I don’t understand this question. “Negotiations should have been completed before the end of a year ago.”
The answer is a year ago must be changed to the year ago.

Could you please explain the difference between the year ago and a year ago?
Why can’t we use a year ago?

 

[GoesStation]

Both versions are ungrammatical and meaningless.

 

[Iamdrachen]

Both versions are ungrammatical and meaningless.

Can you find any mistake in the sentence?

 

[GoesStation]

“Negotiations should have been completed before the end of a year ago.”
The answer is a "a year ago" must be changed to "the year ago".

Could you please explain the difference between "the year ago" and "a year ago"?
Why can’t we use "a year ago"?

Can you find any mistake in the sentence?

"Before" has to refer to a specific time. "A year ago" is approximate. The sentence should say Negotiations should have been completed before the end of last year/2020.

Mark text you're writing about with italics or quotation marks. Your question is incorrect and hard to understand without them.