Sure! Here are 15 fill-in-the-gap questions to practice the use of "a" or "an":
- I saw ___ elephant at the zoo.
- She wants to become ___ artist in the future.
- Can you hand me ___ apple from the basket?
- He is ___ honest person.
- We need to buy ___ new car soon.
- They adopted ___ dog from the shelter.
- Would you like ___ cup of tea?
- It was ___ interesting book to read.
- She is looking for ___ umbrella.
- He gave me ___ unusual gift for my birthday.
- There is ___ university in my town.
- She wants to be ___ engineer when she grows up.
- He found ___ old coin in the garden.
- Do you have ___ hour to talk?
- I watched ___ movie last night.
Feel free to fill in the gaps with "a" or "an"!