Sure! Here are the completed sentences:

54. Nga eats more **unhealthily** than Tung does because she likes fast food. (unhealthier)

55. The **communal** houses of many ethnic groups are used to worship the ancestors. (communual)

56. Most of the Central Highlands is **mountainous**. (mountainous)

57. Do villagers today dress **traditionally** as in the past? (traditionally)

58. I am **interested** in her hometown with a lot of paddy fields. (interested)

Let me know if you need further assistance!