A and an are used with singular countable nouns. A is used before consonants; an, before vowels.
A cat
An ocean
An orange bike
Have a look at the following examples:
An hour (Please note that the h is silent; therefore, hour starts with a vowel sound.)
A hot dog (The h is not mute here.)
A university student ("University" does not begin with a vowel sound, but, with a consonant sound. It is equivalent to saying
you in English.)
An unusual situation (The letter u has a vowel sound here.)
The plural of a or an is some:
Some cats
Some oceans
Some is also used with uncountable nouns: some milk.
In questions and in negatives sentences, any is used instead of some:
There wasn't any milk.
Has she sent you any photos?
However, when we expect a positive reply or when we are offering or asking for something, we use some instead of any:
Would you like some coffee?
Is there some ham in the fridge, mum? I'm very hungry. (The speaker wants to eat some ham, so he or she expects that his or her mother will say "yes".)
The is used to refer to things previously mentioned or to refer to something unique:
A man and a woman were walking along the path. The man was wearing a red jumper and the woman, a pink jacket.
I would like to go to the moon.
Some, any and the are omitted when the names express a general idea:
I love bananas.
Milk is very good for children.
Exercises:
A. Fill in the gaps with a, an, some, any or — (if no article is required).
1. I need __________ volunteer to sweep the sitting-room and the kitchen.
2. Let's buy __________ grapes for the party.
3. May I have __________ water, please?
4. There aren't __________ strawberries.
5. It was __________ easy exam. Everybody passed it.
6. There is __________ lady at the door who asks for you.
7. We don't have __________ coke.
8. She hasn't got __________ friends
9. "Are there __________ trees?"
"No, there aren't __________ (trees). It's a desert place."
10. __________ elephants never forget.
B. Fill in the gaps with a, an, some, any, the or — (if no article is required).
1. __________ onions aren't in __________ cellar. They are in __________ kitchen.
2. __________ whales and __________ elephants are __________ biggest mammals on earth.
3. There were __________ books and __________ comics. __________ books were broken, but __________ comics weren't.
4. "Could you give me __________ sweets, granny?"
"Of course, love!"
5. I've lost __________ crayons I bought yesterday.
6. She hates __________ garlic, but I love it.
7. We would like to spend __________ week in Barcelona.
8. __________ pollution is destroying __________ earth.
9. There isn't __________ apple juice left. Let's buy __________ (apple juice).
10. "Did they drink __________ wine?"
"No, they didn't."
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