This document discusses the differences between subject and object pronouns in relative clauses. It notes that relative pronouns like "who", "which", and "that" are obligatory elements when they are the subject of a subordinate clause, but can be omitted when they are the object of a subordinate clause. Some examples are provided to illustrate this, showing that the relative pronoun is required in some cases and optional in others depending on if it is serving as the subject or object.

1. Subject pronoun or object pronoun?

2. SUBJECT PRONOUN OBJECT PRONOUN
The man who lived next The man who we met
door was very friendly. was very friendly.
subject
object subject
“who” is an obligatory
element “who” is an optional
element (it is the object of
the subordinate clause)

3. SUBJECT PRONOUN OBJECT PRONOUN
This is the bank which This is the bank which
was robbed yesterday. they prefer
object
subject subject
“which” is an obligatory “which” can be omitted
element because it is the object of
the subordinate clause

4. SUBJECT PRONOUN OBJECT PRONOUN
They are playing a song that They are playing a song that
sounds good. we like.
subject subject object
“that” is an obligatory element “that” is an optional element
(it can be inserted or not)

5. The relative pronouns who, which and that
can be omitted when they function as the
object of the subordinate clause.
Note: the relative pronouns where, whose and when cannot
be omitted in a clause.
Analía V. Gozzarino