We have been able reach an agreement, until we find a peaceful solution to the boundary issue.
We are able to reach an agreement, until we find a peaceful solution to the boundary issue.
What is the difference between these two sentences?
We have been able reach an agreement, until we find a peaceful solution to the boundary issue.
We are able to reach an agreement, until we find a peaceful solution to the boundary issue.
What is the difference between these two sentences?
I am afraid that both sentences are incorrect. First, it doesn't seem to make any sense unless you negate the main clause (be able to reach an agreement). And, you also need to make the tenses in both clauses agree with each other.
If you want to talk about a "not happen yet" condition, you could say:
We will not be able to reach an agreement, till we find a peaceful solution to the boundary issue.
If you want to talk about something that has just happened, you could say:
We were not able to reach an agreement, till we found a peaceful solution to the boundary issue.