1, 30 years old: It means that a person should be independent in personality, knowledge and career when he is 30 years old. Now it has become synonymous with a person's thirty years old, used for men.

2. Pinyin: é rl √ zh √ niá n

3. Source: The Analects of Confucius for Politics: "I am determined to learn five out of ten, stand at thirty, and not be confused at forty."

I was determined to learn when I was fifteen. By the age of 30, I know books and reason, and I can do things according to etiquette. At the age of forty, I firmly believe in my words and deeds.