Here are the sentences transformed into questions:

1. **Is Mua sap a popular folk dance of the Thai people?** (yes/no questions)

2. **Did he attend the Dalat Flower Festival last year?** (yes/no questions)

3. **Will we watch a documentary about the Khmer?** (yes/no questions)

4. **What language do the Kinh people speak?** (wh-questions)

5. **How can the visitors get to the Cat Cat village?** (wh-questions)