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"Siéntense" is a form of "siéntense", a phrase which is often translated as "sit". "Por favor" is a phrase which is often translated as "please". Learn more about the difference between "por favor" and "siéntense" below.
por favor(
pohr
fah
-
bohr
)A phrase is a group of words commonly used together (e.g., once upon a time).
siéntense
A phrase is a group of words commonly used together (e.g., once upon a time).
a. sit
No hay sillas suficientes; siéntense en el piso.There aren't enough chairs; sit on the floor.