Question: Not Alone, is Zhang Liyin's which number overall single, Zhang held a showcase to support the release of the single, which was held at the Century Theater in Beijing, EXO members Tao and Chen were guests, Exois a South Korean-Chinese boy group based in Seoul? 
Sentence (from "Not Alone (Zhang Liyin song)"): The song is a remake of 'By Myself' (나 혼자서) from the SBS drama "Ja Myung Go" which "Girl's Generation" member Tiffany sang back in 2009.
Relevant evidence: No