Relative /adjective clause is a clause that modified noun.
• who > subject (person) : I, you, they, we, she, he
• whom > object (person) : me, you, them, us, him, her
• whose > milik (person) my…., your…., their…., our…., his…., her….,
• which > benda/binatang : subject/object
• that > orang/binatang/benda : subject/object (informal)
• of which the > milik (benda/binatang) : its…., their….,
• where > place
• when > time
a. As Subject
1. The boy is kind. He sits under the tree.
The boy who/that sits under the tree is kind.
Note: that (informal)
2. The boy is kind. You helped him yesterday.
The boy whom/that you helped yesterday is kind
Note: whom/that bisa dihilangkan.
3. The boy is kind. You borrowed his car last week.
The boy whose car you borrowed last week is kind
Note: The boy whose car you borrowed last week (subject)
4. The room is hot. We study in it.
The room (which/that) we study in is hot
The room (in which/where) we study is hot
Note: The room (in which/where) we study (subject)
b. As Object/Complement
1. I like the girl. He loves her very much.
I like the girl whom he loves very much.
2. I have a cat. Its fur is nice.
I have a cat of which the fur is nice.
3. I like Harry Potter. It is very popular movie.
I like Harry Potter which is very popular movie.
Source: My note