You also revise how to write a paragraph depending on the cues like this

mất gốc 

Khmer is one of the most crowded ethnic groups in Vietnam. They have the population of approximately 1.3 million. Most of them live in Mekong Delta area. They use Mon- Khmer group as their main language. They do many agricultural activities such as growing rice, making sugar and raising cattle. The Khmer people have many important festivals during the year. Especially, they celebrate two main biggest festivals: Chaul Chnam Thmay and Greeting the Moon.