Basics. Relative Clauses: Who, Which, and That: correct answers
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Relative clauses add essential or extra information to a sentence, but choosing the right relative pronoun can sometimes be tricky. Generally, we use who for people and which for things. The word that can often replace either in defining clauses without commas (e.g., "The man who/that called is here"), but it is strictly forbidden in non-defining clauses with commas (e.g., "My car, which is old, still runs well").
This challenge tests your ability to navigate these grammar rules through a series of highly unusual scenarios. You will practice identifying defining vs. non-defining clauses, using relative pronouns after prepositions (like "in which"), and knowing exactly when to use who, which, or that to describe everything from a rogue smart fridge and a haunted bakery to a screaming parrot.
You'll work through 12 questions featuring a varied mix of single-choice, multi-choice, drop-down, and drag-and-drop formats to master these important sentence connections.
Try the quiz to check your knowledge!
Correct answers
Question 1
Complete the detective's bizarre case notes by selecting the correct pronoun.
I need to question the tall man in the tuxedo _____ was seen feeding expensive caviar to the street cats.
The correct answer is who.
We use who as the subject pronoun for people. Which is only used for things and animals, whom is used for objects (not subjects), and whose shows possession.
Question 2
The correct answers are The old castle, which was built in 1492, is supposedly haunted. and The ghost that haunts the west wing hates loud noises.
Which is correctly used in the first sentence to add extra, non-essential information (a non-defining relative clause).
That is correctly used in the second sentence for a defining relative clause about the ghost.
The third sentence is incorrect because you cannot use that in a non-defining relative clause (after a comma). The fourth is incorrect because which should not be used for people (the tour guide).
Question 3
The office manager _________________________ tried to extinguish the flames completely panicked.
The hot coffee _________________________ she threw on the machine only made the sparks fly higher.
The ancient printer in the hallway, which hasn't been serviced since 2005, suddenly caught fire.
The office manager who tried to extinguish the flames completely panicked.
The hot coffee that she threw on the machine only made the sparks fly higher.
which: Used for things in non-defining clauses (after a comma). That cannot follow a comma here.
who: Used as the subject of the relative clause for a person. (Whom is the object form).
that: Used for things in defining clauses.
Question 4
The correct answers are The smart fridge that ordered 50 gallons of milk is finally unplugged. and The smart fridge which ordered 50 gallons of milk is finally unplugged.
For defining relative clauses about things, both that and which are perfectly correct.
"Who" is incorrect because a fridge is an object, not a person. The sentence with commas is a non-defining relative clause, and we can never use that after a comma in a non-defining clause.
Question 5
The neighbor _________________________ called the police was wearing a superhero onesie.
The suspect's parrot, which is known for screaming at midnight, woke up the entire building.
The neighbor who called the police was wearing a superhero onesie.
Use which (not that) for non-defining relative clauses—the ones separated by commas that add extra, non-essential information about a thing or animal.
Use who as the subject pronoun for people in defining relative clauses. (Whom is used for objects, and which is used for things).
Question 6
Complete the space tourist's postcard back to Earth. Drag the correct words into the gaps.
The zero-gravity pool, which is located on the top deck, is incredibly fun to float around in. The alien staff members who run the gift shop are very friendly, even if they have six tentacles each. I bought a lot of souvenirs because everything that they sell is made of genuine moon rock!
The zero-gravity pool, which is located on the top deck, is incredibly fun to float around in.
Because this is a non-defining relative clause (set off by commas) describing a thing, we must use which. Where would require a subject to follow it (e.g., where I swim).
The alien staff members who run the gift shop are very friendly...
We use who for people (or personified beings like intelligent aliens) when they are the subject of the relative clause.
...everything that they sell is made of genuine moon rock!
After indefinite pronouns like everything, anything, nothing, or all, we strongly prefer that over which. What cannot be used as a relative pronoun following a noun or indefinite pronoun.
Question 7
The waiter, _________________________ had clearly never balanced a tray before, immediately dropped the bowl right onto my lap.
I bravely ordered the soup that was glowing a mysterious shade of neon green.
The waiter, who had clearly never balanced a tray before, immediately dropped the bowl right onto my lap.
Use that for defining relative clauses about things (like soup). Who and whom are only used for people.
Use who for non-defining relative clauses about people. You cannot use that immediately after a comma in a non-defining relative clause.
Question 8
The correct answers are who and that.
In a defining relative clause describing a person, you can use either who or that as the subject pronoun.
Which is only used for things or animals, and whom is used when the person is the object of the clause, not the subject.
Question 9
Choose the right word to finish the overly honest real estate agent's listing.
This is the creepy Victorian mansion in _____ the previous owners claimed to see flying teacups.
The correct answer is which.
When a relative pronoun directly follows a preposition (like "in", "on", or "about"), we must use which for things or whom for people. We cannot use that directly after a preposition (e.g., "in that" is incorrect here), and "in where" is grammatically invalid.
Question 10
Complete the journalist's notes about a very strange local scientist. Drag the correct words to complete the sentences.
The new machine, which is powered entirely by old coffee beans, makes a terrible sputtering noise. However, the assistant who helps him operate it doesn't seem to mind the smell. Honestly, it is the most ridiculous invention that I have ever seen!
The new machine, which is powered entirely by old coffee beans, makes a terrible sputtering noise.
We use which (not that) for non-defining relative clauses—the ones separated by commas that add extra, non-essential information about a thing.
However, the assistant who helps him operate it doesn't seem to mind the smell.
We use who as the subject pronoun for people.
Honestly, it is the most ridiculous invention that I have ever seen!
We use that for things in defining relative clauses. It is especially preferred after superlatives like "the most ridiculous."
Question 11
Help the new employee understand the office dynamics by choosing the correct word.
The breakroom coffee machine, _____ sounds like a dying pterodactyl, makes surprisingly excellent espresso.
The correct answer is which.
Because the clause is separated by commas (making it a non-defining relative clause that adds extra information), we must use which for things. We cannot use that after a comma in a relative clause!
Question 12
Help the food critic finish her rather unusual restaurant review. Match each blank with the appropriate relative pronoun.
The sourdough bread, which rises completely on its own at midnight, is absolutely delicious. I managed to speak to the baker who works the night shift to ask for the recipe. He just smiled and gave me a special glowing pastry that cures hiccups instantly.
The sourdough bread, which rises completely on its own at midnight, is absolutely delicious.
Commas indicate a non-defining relative clause. We must use which for things in these clauses; that is never used after a comma in this way.
I managed to speak to the baker who works the night shift to ask for the recipe.
Who is the correct subject relative pronoun for people. Whom is only used for the object of a clause.
He just smiled and gave me a special glowing pastry that cures hiccups instantly.
That is used for things in defining relative clauses. Who and whose are for people.