1. The lights are on at three o'clock and the chicken is on at five o'clock. It's when men are studying. Black-haired people don't know how to study early, and white-haired people regret studying late. ——Yan Zhenqing.

2. An inch of time is worth an inch of gold, but an inch of gold cannot buy an inch of time.

3. It is easier for a young man to learn than to become an old man, so no time is wasted. ——Zhu Xi.

4. My life has a limit, but my knowledge has no limit. ——Zhuangzi.

5. If young people don’t work hard, old people will be sad. ——"Long Song Xing".

6. There are three paces of time: the future arrives belatedly, the present flies by like an arrow, and the past stands still forever. ——Schiller.