B. Non-defining relative clauses

We use a non-defining relative clause to give extra information about the subject or object of the sentence. In writing, the use of commas is crucial as they separate these clauses.

• My husband, who is in Paris on a business trip, sent me a bouquet of flowers.
  → We could leave out the relative clause and the meaning would still be clear.
  → In a non-defining relative clause, we cannot leave out the relative pronoun.