1. 用a 或 an 填空。

1. （1） There's computer on the desk.
   

3. （2） This is orange. That's apple.
   

5. （3） I have egg. It's yellow egg.
   

7. （4） There's octopus. It's small octopus.
   

9. （5） Which do you prefer, umbrella or raincoat?