Answer:
1. We see the moon at night.
2. Kitty put an ice cube in her lemonade.
3. The Book you want is not in the library.
4. This is a peacock. The peacock has colourful feathers.
5. May I have an envelope? I will put my letter in the envelope.
6. Peter bought a new bike. The bike is red and black.
7. There is an orchard nearby. The orchard has many apple trees.
8. The Ganges is a holy river.
9. Can I have a piece of cake? The cake is very tasty.
10. Priti bought a new raincoat. The raincoat is transparent
Explanation: If the next word begins with a vowel a,e,i,o,u or sometimes h, use an.
* A peacock has colourful feathers. is also acceptable.
5. May I have the envelope? is also acceptable if there is only one envelope available.
5. May I have an envelope?
8. The Ganges is a holy river. In the USA we pronounce "holy" with an aspirated "h" so a holy river. There are some places where "holy" is pronounced with an unaspirated "h" so they would write an holy.
We would write The train will arrive in an hour. H is not aspirated in "hour."