2. First, let'sstudy the rules:
A and An are articles, they are used with singular nouns.
A and An = 1
For example: a book = 1 book
an apple = 1 apple
But how do we know when to use a and when to use an?
It’s simple:
Use A with words that begin with a consonant sound :
a cat /k/ a house /h/ a universe /y/ a ball /b/
Use An with words that begin with a vowel sound:
an ape /e/ an hour /a/ an injection /i/ an ugly man /Λ/