数学求平均值公式简介：The old man was a little dissatisfied in his heart, but he was not as surprised as he was at the beginning. During this period, he had food and a place to live, and the faces of his grandparents and grandson looked better.
The old man was a little dissatisfied in his heart, but he was not as surprised as he was at the beginning. During this period, he had food and a place to live, and the faces of his grandparents and grandson looked better.
