What silent promise did Adeline make to Yeye after the incident with the encyclopedias in Chinese Cinderella by Adeline Yen Mah?

In "Chinese Cinderella" by Adeline Yen Mah, after the incident with the encyclopedias, Adeline made a silent promise to her grandfather, Yeye, to never reveal the truth about what happened. This promise was a sign of respect and loyalty to her grandfather, as well as a way to protect him from potential consequences. Adeline's decision to keep this secret demonstrates her understanding of the importance of family honor and the complexities of familial relationships in the context of Chinese culture.