Итак, вспомним-ка эту тему.
The используется, если мы говорим о чем-то определенном.
A / an используется в зависимости от того, на какую букву начинается существительное. Означает неопределенность. Во множественном числе не используется.
My son is a pupil.
He's a good pupil.
You have some pencils, but I have no pencils.
My granny often tells us long interesting stories.
I have a sister. My sister is an engineer. My sister's husband is a doctor.
I can see a pencil on your table, but I can see no paper.
He hasn't got a car. But he's got a computer. The computer is new.
We wrote a dictation yesterday.The dictation was long.
She has a ball. The ball is big.
Do you like an ice-cream?
My cousin is upset. He's got a sore throat.
What's your name? My name is Alison.
What's the name of this village?
There is a small computer in front of the books there.