A OR THE? EXERCISE 1 (ESL)

Grammar review A vs the — the core distinction

English has two articles: the indefinite article (a/an) and the definite article (the). Knowing which to use comes down to one key question: is the noun specific and known, or general and new?

Use A/AN when:
• You are introducing something for the first time: “I saw a dog in the street.”
• The noun is one of many, not a specific one: “She works in a hospital.”
• Describing someone’s job or role: “He is a teacher.”

Use THE when:
• The noun has already been mentioned: “I saw a dog. The dog was barking.”
• Both speaker and listener know which specific thing is meant: “Please close the door.”
• There is only one of something: “The sun rises in the east.”
• With superlatives: “She is the tallest person in the room.”

Use AN (not A) before vowel sounds:
an apple, an hour, an honest person — note it’s the sound, not the letter, that matters.