Industry is good at diligence, but he is poor at playfulness.

Black hair doesn't know that he is diligent early, but he who turns himself in regrets that he is late in studying. (Yan Zhenqing)

It's hard for a teenager to learn old age, and an inch of time can't be wasted.

An inch of time is worth an inch of gold, but it's hard to buy and save time with money.

When books come to use,