I saw a dog in the park.

Used to refer to a single item or one of a group.
I need a pen to write.
She has a cat at home.
Can you give me a book?
a car
a friend
a house
one
any
single
I saw a dog in the park.

Used to refer to a single item or one of a group.
I need a pen to write.
She has a cat at home.
Can you give me a book?
a friend
a chance
a problem
one
single
any
A is the first letter.

The first letter of the English alphabet.
A is for apple.
The grade A is the best.
She chose A for her answer.
letter A
grade A
note A
first letter
alpha
beginning