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"Sea lo que sea" is a phrase which is often translated as "whatever it is", and "pase lo que pase" is a phrase which is often translated as "whatever happens". Learn more about the difference between "sea lo que sea" and "pase lo que pase" below.
sea lo que sea(   
seh
-
ah
loh
keh
seh
-
ah
)A phrase is a group of words commonly used together (e.g., once upon a time).
a. whatever it is 
Sé que algo te preocupa. Sea lo que sea, dímelo, y a lo mejor te puedo ayudar.I know something is bothering you. Whatever it is, tell me, and maybe I'll be able to help.
a. whatever he is  (masculine)
Por lo visto es abogado, pero sea lo que sea, es un inculto.It seems he's a lawyer, but whatever he is, he's so ignorant.
b. whatever she is  (feminine)
Es la jefa. - Sea lo que sea, no veo por qué tiene que hablarnos así.She's the boss. - Whatever she is, I can't see why she should talk to us like that.
c. whatever it is 
Es un edificio modernista. - Sea lo que sea, es horroroso.It's a modernist building. - Whatever it is, it's awful.
3. (formal) (regardless of your status; second person singular)
A word or phrase used to refer to the second person formal “usted” by their conjugation or implied context (e.g., usted).
a. whatever you are 
No olvide que el médico soy yo. - Sea lo que sea, usted no sabe nada. Yo lo he buscado en Internet.Don't forget I'm the doctor here. - Whatever you are, you don't know a thing. I've searched for it in the Internet.
pase lo que pase(   
pah
-
seh
loh
keh
pah
-
seh
)A phrase is a group of words commonly used together (e.g., once upon a time).
1. (general)
a. whatever happens 
Pase lo que pase, ya sabes que puedes contar conmigo para cualquier cosa que necesites.Whatever happens, you know you can count on me for anything you need.
b. come what may 
Yo creo que, pase lo que pase, ninguno de los directivos va a dimitir.I think that none of the managers will resign, come what may.