Which episode did the new version of Zhu Huan Gercom first hear Wei Zi write?

In the new version of Princess Zhu Huan, Er Kang first heard Wei Zi write in the first 15 episode. In this episode, Wei Zi wrote a line on his hospital bed, which Erkang secretly saw. This scene happened when Wei Zi was ill. Er Kang secretly observed Wei Zi's actions to confirm her identity and authenticity.