This summer vacation, the teacher asked a wonderful question, whether the rabbit runs fast up the mountain or down the mountain. I said I was running down the hill, but the teacher's answer was quite wonderful. "Rabbits run faster up the hill than down the hill. Because the rabbit's front legs are shorter than its rear legs, it is equivalent to reducing the slope of the mountain when going up the mountain, which is more labor-saving. When going down the mountain, the rabbit is not easy to stand still. If it runs too fast, it is easy to lose its balance and roll down the mountain. For safety, rabbits have to slow down. " . . .