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"Las dos" is a form of "las dos", a phrase which is often translated as "two". "Cuarto" is an adjective which is often translated as "fourth". Learn more about the difference between "las dos" and "cuarto" below.
las dos(
lahs
dohs
)A phrase is a group of words commonly used together (e.g., once upon a time).
a. two
Tengo una cita con el doctor a las dos, y con este tráfico no sé si voy a llegar.I have a doctor's appointment at two, and with this traffic I'm not sure I'm going to make it.
b. two o'clock
¿No ibas a ir a almorzar con tu papá hoy? Ya son las dos.Weren't you going to have lunch with your dad today? It's already two o'clock.
2. (feminine) (with "two" used as an adjective)
A word or phrase that is feminine (e.g., la manzana).
a. the two
¿Francis Ford Coppola dirigió "El padrino" o "El padrino II"? - El dirigió las dos.Did Francis Ford Coppola direct "The Godfather" or "The Godfather Part II"? - The two were directed by him
b. both
No puedo decidir si pedir la empanada o la arepa, así que voy a pedir las dos.I can't decide whether to get the empanada or the arepa, so I'm going to order both.
cuarto, el cuarto(
kwahr
-
toh
)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).