The old man was quite satisfied with Gu Pan's attitude, "You young people still lack life experience, so you must learn more from your elders in the future. You need to be open-minded. You don't know the benefits of the sun, do you? I happen to have time today, so I'll teach you."
Without waiting for their response, the old man began, "First of all, sunlight can prevent skin diseases; secondly, it can enhance physical fitness and can also provide calcium; lastly, it can promote metabolism and relieve stress. Do you know why sunlight can treat skin diseases?"
Seeing that they did not speak, the old man continued, "Because sunlight contains ultraviolet rays, and ultraviolet rays can disinfect. Then do you know why it can supplement calcium?"
Saying so, he pointed to Gu Pan, "You answer."