C51 He Had to Make the Principal Expel You!

"How could you possibly know that..." Lee Xin was utterly impressed by Su Wen, staring at him in disbelief. He had been racking his brain trying to figure out what ingredient was missing, but he just couldn't remember. To his amazement, Su Wen not only knew but could also deduce the illness it was meant to treat from such an incomplete prescription.

"It's quite simple