She is at the doctor's
Where is your sister?
She is at the doctor's because she is ill.
I would like to guess if "at the doctor's" is the correct expression.
2 Answers
¡Hola!, Nila:
You are correct.
"She is as the doctor's' is correct.
Muchos saludos/Best Regards,
Moe
Also Nila, not quite the same but "she has gone to the doctor´s", just in case you are not sure whether she has arrived .