A - AN
If you have to use a or an, depends on the sound the word begins with.
If the first sound is a consonant you have to use a.
If the first sound is a vowel you have to use an.
|ice - cream|
|an hour - because the first letter is silent and the word starts with an au-sound.|
|a uniform, a university - because the first letter starts with a ju-sound.|
|Exercise 1||Exercise 2||Exercise 3|