Articles: "A/ AN/ THE"

Indefinite Articles: A/AN

The form "a" is used before consonant sounds and the form an before vowel sounds. When saying abbreviations like "FM" or "UN", use "a" or "an" according to how the first letter is said. For example, F is a consonant, but begins with the sound /e/ and so you say: an FM radio. U is a vowel but begins with /j/ and so you say: a UN declaration. The names of letters: "f, h, l, m, n, s, x" begin with vowel sounds, so abbreviations that begin with one of these letters are treated as stating with a vowel. Ex: an MP, an HGV...
"A or an" is usually followed by a singular countable noun.

• Used before countable or singular nouns referring to people or things that have not already been mentioned: There's a visitor for you. She's a friend of my father's (= one of my father's friends).
• Used before uncountable nouns when these have an adjective in front of them, or phrase following them: A good knowledge of French a sadness that won't go away.
• Any, every: A lion is a dangerous animal.
• Used to show that sb/sth is a member of a group or profession: Their new car's a BMW. She's a Buddhist. He's a teacher. Is that a Monet (= a painting by Monet)?
• Used in front of two nouns that are seen as a single unit: A knife and fork.
• Used instead of one before some numbers: A thousand people were there.
• Used when talking about prices, quantities and rates. SYN per: They cost 50p a kilo. I can type 50 words a minute. He was driving at 50 miles an hour.
• A person like sb: She's a little Hitler. Used before the name of the famous person to mean someone else with abilities, appearance, or character: Already he is being hailed as a young Albert Einstein.
• Used before sb's name to show that the speaker does not know the person: There's a Mrs Green to see you.
• Used before the names of days of the week to talk about one particular day: She died on a Tuesday.
• Used before the name of drinks to mean a cup or glass of that drink: I will just have a beer. Have you got time for a coffee?

Definite Article: THE

• Used to refer to sb/sth that has already been mentioned or is easily understood: There were three questions. The first two were relatively easy but the third one was hard.
• Used to refer to sb/sth that is the only, normal or obvious one of their kind: The Mona Lisa, the Nile the Queen. What's the matter? The phone rang. I patted her on the back.
• Used when explaining which person or thing you mean: The house at the end of the street. The people I met there were very friendly. It was the best day of my life. You're the third person to ask me that. Friday the thirteenth. Alexander the Great.
• Used to refer to a thing in general rather than a particular example: He taught himself to play the violin. The dolphin is an intelligent animal. They placed the African elephant on their endangered list. I'm usually out during the day. I heard it on the radio.
• Used with adjectives to refer to a thing or a group of people described by the adjective: With him, you should always expect the unexpected. The unemployed, the French
• Used before the plural of sb's last name to refer to a whole family or a married couple: Don't forget to invite the Jordan.
• Enough of sth for a particular purpose: I wanted it but I didn't have the money.
• Used with a unit of measurement to mean "every": My car does forty miles to the gallon. You get paid by the hour.
• Used with a unit of time to mean "the present": Why not have the dishes of the day? She's flavour of the month with him.
• Used, stressing the, to show that the person or thing referred to is famous or important: Sheryl Crow? Not "the Sheryl Crow? At that time London was the place to be.
• Use "the" before words such as "school, university, and prison" when you are referring to a particular building: Inspectors will be visiting the school next week. In American English, however, "the" is used with "hospital" for referring to the institution in general: She was admitted to the hospital with minor head injuries.

Note: DON'T use "the"

• When you are referring to the institution in general: her husband has been sent to prison for 3 years.
• When you are talking about travelling by a particular form of transport: We went by plane.
• When you are referring to things or people in a general way: Children need love and attention.
• Before the names of individual mountains, the names of streets, towns, counties, states, or continents: Mount Everest. My parents live in Surrey. There are a few exceptions: The Sudan, the USA, The Hague.
• Before a person's name when it is used in the possessive: The car was parked in front of Jim's house.
• Before the names of meals: Dinner is at 7:30. What are we having for lunch?

Idioms
The more, the less, etc. ..., the more, the less, etc. ...: Used to show that two things change to the same degree: The more she thought about it, the more depressed she became. The less said about the whole thing, the happier I'll be.