C190 Forget birthday(part iib)

Why did Liza change the 28th of April to the 5th of May? This question puzzled Zi Peng; he was confused; he felt somewhat puzzled. He had made all sorts of guesses about this question, but none had been right. When he was about to go down the mountain, he suddenly came to his senses. Oh! Oh right, today is little sister's birthday! Right! It was her thirty-eighth birthday. At this moment