El adjetivo en función de Atributo

El adjetivo en función de atributo es invariable en género y en número. Se coloca siempre delante del sustantivo al cual se refiere.

That is a famous writer.                      Those are famous writers.
She’s a pretty girl.                               They are a pretty girls.
This is an old house.                            These are old houses.

Sin embargo, cuando el adjetivo tiene función de predicado se coloca después del sustantivo al cual se refiere.

This writer is famous.

--- PARA PROFUNDIZAR EN EL TEMA ---

There are two main kinds of adjectives: attributive ones normally come right before the noun they qualify, while predicative adjectives come after to be or similar verbs such as become and seem. Most adjectives can serve either purpose: we can speak of a ‘happy family’ and say ‘the family appeared happy.’ But some work only one way. Take the sentence ‘Clergymen are answerable to a higher authority.’ Answerable is exclusively a predicative; you could not refer to an ‘answerable clergyman.’ And higher is strictly attributive; you wouldn’t normally say, ‘The authority is higher.’