Articles冠词

A，an and the are articles.

(a) A/An
A is used:

(i) with words beginning with a consonnant sound (辅音）
Example：a cat, a nurse, a playground, a futscal court

(ii) with words beginning with the 'yu' sound
Example: a university, a uniform

An is used:
(i) with words beginning with a vowel sound （元音）
Example: an aquarium, an egg, an ostrich, an island

(ii) with words beginning with the silent 'h'（ 隐音‘h'）
Example: an honest boy, an hour

(b) The
The is used:
(i) when we speak of the same thing or person for the second time.（重复提到的同一个物体或人）
Example: My grandmother has a farm. The farm is big.

(ii) when we speak of things that are the only of its kind.（独一无二的物体）
Example: The moon shines brightly at night.

(iii) when we refer to a particular person, animal or thing:(特指的一个人、动物或东西）
Example: Please pass the bottle of tomato sauce to me.

(iv) before the superlative degree of an adjective.(最高级)
Example: My sister is the tallest girl in my family.