Love. According to official website, Sina News, songs A, B, C and D represent love and refer to passers-by in the love world. "A, B, C, D" is a song composed and arranged by Li and sung by Jacky Cheung. Lyrics excerpt: a rare good mood, suddenly sunny weather, as if love may appear at any time, as if every face is very pleasing to the eye, as if everyone has two childhoods, as if we are willing to do what we say, we are just passers-by and play together in this colorful world.