Fill in a or an. It is a book. 1. It is ___ interesting book. 2. It is ___ very interesting book. 3. He is ___ actor. 4. He is ___ good actor. 5. Have you got ___ envelope? 6. Have you got ___ big envelope? 7. Give me ___ oar, please. 8. Give me ___ small oar, please. 9. She has got ___ apple and pineapple. 10. I need ___ onion. 11. I need ___ big onion. 12. This is ___ umbrella. 13. It is ___ very nice umbrella.