Two: if the young don't work hard, the old will be sad.

Three: the song never leaves the mouth, and the fist never leaves the hand.

One: three days without reading, three days without being a novice: for a reader, it means reviewing books frequently. The second sentence was said by the rival artist. If the craft is put down for a period of time, it will be unfamiliar and not smooth. The affirmative sentence means to review the past and learn the new.

Two: if the young don't work hard, the old will be sad. They all say that they don't work hard when they are young and strong. It's no use being sad when you are old. Source "Yuefu Poems and Long Songs": "When will a hundred rivers go east to the sea and return to the West? If you don't work hard, the boss will be sad. " Han Yuefu lived in the Han Dynasty.

Three: the song never leaves the mouth, and the fist never leaves the hand from the tip of the knife. Interpretation means that singers should often sing and martial arts practitioners should often practice. Metaphor means that only by studying hard and practicing hard can you master kung fu.