vs 

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"Si" is a form of "si", a conjunction which is often translated as "if". "Por favor" is a phrase which is often translated as "please". Learn more about the difference between "si" and "por favor" below.
si(
see
)
A conjunction is a word that connects words, phrases, clauses, or sentences (e.g., The cat and the dog slept.).
conjunction
a. if
Si llueve mañana, cancelaremos el pícnic.If it rains tomorrow, we will cancel the picnic.
a. whether
Preguntó si me estaba divirtiendo.He asked whether I was enjoying myself.
b. if
Paco quiere saber si Laura también va a asistir.Paco wants to know if Laura is also going to attend.
A masculine noun is used with masculine articles and adjectives (e.g., el hombre guapo, el sol amarillo).
masculine noun
a. B
Primero lo oí en si menor.I first heard it played in B minor.
b. ti (solfége)
Practiquemos las escalas en orden inverso: do, si, la...Let's practice scales in reverse order: do, ti, la...
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por favor(
pohr
 
fah
-
bohr
)
A phrase is a group of words commonly used together (e.g., once upon a time).
phrase
a. please
Dame comida, por favor.Give me food, please.
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