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"Cuarto" is an adjective which is often translated as "fourth", and "a las nueve" is a phrase which is often translated as "at nine". Learn more about the difference between "cuarto" and "a las nueve" below.
cuarto, el cuarto()
An adjective is a word that describes a noun (e.g., the big dog).
a. fourth
Entra al edificio y toma el ascensor al cuarto piso.Enter the building and take the elevator to the fourth floor.
A masculine noun is used with masculine articles and adjectives (e.g., el hombre guapo, el sol amarillo).
a las nueve()
A phrase is a group of words commonly used together (e.g., once upon a time).
a. at nine
La película empieza a las nueve. Hay que darse prisa o nos la perdemos.The film starts at nine. We'd better hurry or we'll miss it.
b. at nine o'clock
A las nueve sonaron las campanas de la iglesia.The church bells chimed at nine o'clock.
