What does Xia Yuhe mean by Daming Lake?

Meet Xia in Daming Lake. Summer by Daming Lake comes from the princess. In the play, (with Xia's daughter) went to Beijing to find relatives with her mother's wishes after her death, hoping to find her father before her death and fulfill her wishes. After many twists and turns, she finally came to the palace to meet the emperor, took out a token and asked the emperor if he still remembered Xia Yuhe by Daming Lake. Summer by Daming Lake in the play was meant to ask if you still remember the summer by Daming Lake.