Gu Yanmo went abroad to study. Before going abroad, he said to Su Qingli: "When I come back, I will take you to see the Aurora." Su Qingli nodded and agreed, but Gu Yanmo didn't know that Su Qingli was holding on to the ticket to Antarctica. Five years later, they reunited and went to complete the Aurora they agreed to see five years ago.
Purpose: We must do what we say, and we must not break our word.