A Subordinate Relative Clause is one that determines the meaning of an element that is connected to it by a nexus that makes reference to an element of the main clause and works as a subject or complement of the subordinate clause.
Depending on the element that the nexus makes reference to (antecedent) there are three of them:
who → if the element is a person.
- That is the girl who Mario loves.
which → if the element is a thing.
- You leave in the train which leaves at 10.
where → if the element is a place.
- The library is where you can borrow books.
There are two types of Relative Subordinate Clauses: Defining and Non-defining.
Defining relative clauses are those that clarify the reference from the main sentence.
- The woman who is sitting there is my granny.
Non-defining relative clauses are those that just give additional, non-important information about the reference in the main sentence. It is usually (not always) inserted in between commas.
- The woman, who is blonde, is my granny.
There are two more connectors (nexus):
whose: It expresses belonging.
- That is my aunt whose actual address I don't know.
that: It is a universal nexus for Relative Subordinate clauses that have who or which as nexus..
- That is the girl that Mario loves.
- You leave in the train that leaves at 10.