Consider the main premise as follows,
A boy borrowed a pen from a girl. 男の子は女の子にペンを借りました。
Now consider the following additional premises, each with a different conclusion:
The boy is Suzuki Shin.
The boy who borrowed a pen from a girl is Suzuki Shin.
The girl is Hayashi Aimi.
The girl from whom a boy borrowed a pen is Hayashi Aimi.
The pen is expensive.
The pen that a boy borrowed from a girl is expensive.
I am not quite sure the second case above is correct, what do you think?
Can we use a passive form in relative clauses? For examples:
The pen that was borrowed by a boy from a girl is expensive.
Warning: I am not sure this passive form is correct.