1. Historical origin: Vietnam was once a vassal state of China, so in history, Vietnam has close ties with China. Some Vietnamese can speak Chinese, mainly because their ancestors had exchanges with China in history.
2. Cultural exchange: With the passage of time, the cultural exchange between Viet Nam and China has been increasing. In Viet Nam, many people learn Chinese to better understand the culture, history and language of China.
3. Economic development: In recent years, Vietnam's economy has developed rapidly, and its trade with China is also increasing. Some Vietnamese learn Chinese in order to better communicate with customers in China in business communication.
4. Education: In Vietnam, Chinese has become an important subject and has been included in the curriculum of primary and secondary schools and universities. Some Vietnamese learn Chinese because of the need of education.
In a word, there are many reasons why Vietnamese can speak Chinese, including history, culture, economy, education and other factors.