The last poem "You never know when you are old" is that teenagers don't know how to study hard. "It is too late to learn when you are old" means that you don't study hard and diligently when you are young, and you will regret it when you wait until the future. Absorbed in reading, I know that spring is over, every inch of time is like an inch of gold precious. From Wang Zhenbai's Two Poems of Bailudong (Part I).