Article a/an

The indefinite article is the a is the same for all genders.
a boy, a girl, a cat

The indefinite article has no plural form.
a boy - boys

We use an if the following word starts with a vowel.

the following word starts with a consonant	the following word starts with a vowel
a boy	an aunt
a school	an old school
a girl	an American girl

Mind the pronunciation of the following word.

a unit	an uncle
This u sounds like a consonant, so we use a.	This u sounds like a vowel, so we use an.

 Use of the indefinite article a/an

- before phrases of time and measurements (per week/weekly)

We have English 4 times a week.

I go on holiday twice a year.

Our car can do 220 kilometers an hour.

Tomatoes are RM2.00 a kilo.

- before phrases of jobs

My father is a car mechanic.

- with a noun complement

He is a good boy.

- before phrases of nationality

Bruce Springsteen is an American.

- half/quite

We need half a pound of sugar.

This is quite a good story.