Final answer:
The correct preposition to use in this sentence is 'on', as in 'on New Year's Eve'.
Step-by-step explanation:
Answer:
There are usually a lot of parties on New Year's Eve.
The correct preposition to use in this sentence is on. We use 'on' to indicate a specific day or date, such as 'on Monday' or 'on May 1st'. So in this case, we would say 'on New Year's Eve' to indicate that the parties happen specifically on that day.
Example:
There will be a big party on New Year's Eve with fireworks and live music.
Learn more about prepositions