Here are the correct forms of the words in brackets:

1. A trip to Fan Si Pan is an **unforgettable** experience. (forget)
2. You can watch (tradition) **traditional** when you visit Sa Pa. (tradition)
3. Many visitors think that the greatest **attraction** in Hue is temples. (attract)
4. You must take an umbrella because it's **rainy** in Mui Ne at this time of year. (rain)
5. Hue is near Da Nang, but it's more **interesting** than Da Nang. (interest)
6. The Perfume River is the most **famous** river in Central Viet Nam. (fame)
7. You can join many exciting **activities** during the festival. (act)
8. A butterfly is more **colorful** than a moth. (colour)
9. Nam's brother is a **photographer**. He took that picture. (photograph)
10. Excuse me. I'd like some **information** about the cruise. (inform)
11. I find the enormous **diversity** of life on earth quite overwhelming. (diverse)
12. I find the enormous **essence** of life on earth quite overwhelming. (essence)

Feel free to ask if you have more questions!