Relative clauses add information about a noun using pronouns like who, which, that, whose, and where. They can be defining (essential to the meaning) or non-defining (extra information set off by commas). Getting the pronoun and comma usage right is a key advanced skill.
Use who or that for people, which or that for things, whose for possession, where for places, and when for times. In defining clauses, that can replace who/which. In non-defining clauses (with commas), that is not used — you must use who or which. When the pronoun is the object of the clause, it can be omitted in defining clauses: "The book (that) I read was excellent."
Practice
The professor ___ taught me statistics won a Nobel Prize.
The hotelwe stayed was absolutely beautiful.
Combine into one sentence using the correct relative pronoun:
A defining relative clause identifies which specific person or thing you mean. It is essential to the meaning and has no commas: "The students who passed can move on." A non-defining clause adds extra information about a noun that is already specific. It is set off by commas and can be removed without changing the core meaning: "My sister, who lives in Toronto, is visiting next week."
Practice
Which sentence is correctly punctuated?
The reportI submitted yesterday contained a major error.
Put the words in the correct order (non-defining clause):
Relative clauses are a key tool for joining two sentences elegantly. "I have a colleague. She speaks five languages." → "I have a colleague who speaks five languages." Find the noun that appears in both sentences, replace it with the appropriate relative pronoun, and embed the second clause into the first.
Practice
Combine: "This is the café. I first met my partner here." Put the combined sentence in order:
Combine: "She works for a company. The company was founded in 1985." Which is correct?
The scientistresearch led to the vaccine received an award.