In the name of GOD
For people: who/that (فاعلی)
whom (مفعولی)
For things: which/that
Example:
- she is the doctor.
- she did a surgery on my cousin.
- she is the doctor who did a surgery on my cousin.
she is the doctor.
I met her yesterday.
she is the doctor whom i met yesterday.
Mary loves rock music.
She is interested in this type of music.
Rock music is the type of music which mary is interested in.
Rock music is the type of music in which mary is interested.