Here are the suggested words to fill in the blanks:

1. **varies**
2. **shopping**
3. **goes on**

So the completed text would read:

"Christmas is one of the earliest festivals that have been celebrated for years all over the world. The time of celebration (1) **varies** in different countries. In the UK, the festive runs for 12 days after the Christmas day. During this period, people feast and make merry and this ends at the ends of the twelfth day. During Christmas, people enjoy (2) **shopping**, meeting each other, among other fun activities. The celebration (3) **goes on** until New Year’s Day. Many people use symbols to..."