Is "This is a tie which I bought yesterday" right? Or, should it "This is the tie which I bought yesterday?"
"The tie" is the most likely, but it all depends on whether your listener is familiar with fact that you bought a tie yesterday. If they are, then "the tie" is fine -- otherwise "a tie" is what you need. Incidentally, why is your question entitled "Relative pronoun"?
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"The tie" is the most likely, but it all depends on whether your listener is familiar with fact that you bought a tie yesterday. If they are, then "the tie" is fine -- otherwise "a tie" is what you need.
Incidentally, why is your question entitled "Relative pronoun"?