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"Si" is a form of "si", a conjunction which is often translated as "if". "La" is a definite article which is often translated as "the". Learn more about the difference between "la" and "si" below.
la(
lah
)A definite article is a word that identifies a noun as specific or known to the speaker (e.g., the girl).
a. the
La pelota está en el tejado.The ball is on the roof.
La leche está en el refrigerador.The milk is in the refrigerator.
A pronoun is a word that stands in for a noun (e.g., she).
A masculine noun is used with masculine articles and adjectives (e.g., el hombre guapo, el sol amarillo).
si(
see
)A conjunction is a word that connects words, phrases, clauses, or sentences (e.g., The cat and the dog slept.).
A masculine noun is used with masculine articles and adjectives (e.g., el hombre guapo, el sol amarillo).