谁知道为什么用"doctor's"?

谁知道为什么用"doctor's"? she had been at the doctor's for a long time为什么用doctor's Where is your aunt?She is at the doctor‘s.为什么用doctor’s 谁知道 中国品牌为什么要投资韩剧《Doctor异乡人》? the doctor saved a lot of people's lives为什么用lives?、 An apple a day keeps the doctor away为什么doctor不加s Doctor's day是什么? at doctor's doctor's office 看医生用英语怎么说是go to the doctor's还是go to the doctor 博士为什么叫doctor 谁知道做这英语题括号部分提问.is a doctor.She's in Class 2,《Grade 1》His boo