The indefinite article a/an

- There is ____________________ green English book on the desk .
- She's reading ____________________ old comic .
- They've got ____________________ idea .
- He is drinking ____________________ cup of coffee .
- The girl is ____________________ pilot .
- Leipzig has ____________________ airport .
- This is ____________________ expensive bike .
- Look ! There's ____________________ bird flying .
- My father is ____________________ honest person .
- My friend likes to be ____________________ astronaut .