Don't Drop the Subject: Relative Pronouns (who, which, that)
Grammar Rule in 30 Seconds
In English, you can never delete a relative pronoun (who, which, that) if it acts as the subject of the following verb.
- Use 'who' for people and 'which' for things; 'that' works for both in informal speech.
- If the pronoun is followed immediately by a verb, it is the subject: 'The man who lives here.'
- Never omit the subject pronoun: 'The man lives here' is wrong if you mean 'The man who lives here.'
Overview
Use "who," "which," or "that" to join two ideas. They give more information about a person or thing.
You cannot remove these words. Every sentence needs a person or thing to do an action.
This helps you talk about people and things clearly.
How This Grammar Works
who | People | Used exclusively for people or personified animals acting as the subject. |The engineer who designed the bridge was honored. (who = person, subject of designed). The software which crashed suddenly caused data loss. (which = thing, subject of crashed). And The team that won the championship celebrated all night. (that = people, subject of won).that is flexible, who is often preferred for people in more formal contexts, and which is standard for non-human referents.Formation Pattern
who / that):
The professor who teaches advanced physics is brilliant.
which / that):
The documentary which explores climate change is highly recommended.
The mobile app that simplifies language learning is invaluable.
When To Use It
- To identify a specific individual:
I need to speak to the managerwhohandles customer complaints.(Withoutwho handles customer complaints, it's unclear which manager you mean.)- To specify a particular item:
The reportthatwas submitted yesterday contained critical data.(This differentiates it from other reports.)- To describe a unique characteristic:
Our team is developing a new productwhichsolves a long-standing industry problem.(This clause defines the product's key feature.)
The person who called me is my colleague. | No | who is the subject of called. |The person (who/whom/that) I called is my colleague. | Yes | I is the subject of called; who/whom/that is the object. |Common Mistakes
- 1Dropping the Subject Relative Pronoun: This is arguably the most prevalent and significant error. When
who,which, orthatfunctions as the subject of the relative clause, its removal renders the clause grammatically incomplete, as the verb would lack a performer. This often happens because learners mistakenly apply the rule for object relative pronoun omission.
- Incorrect:
I met a programmer writes amazing code.(The verbwriteshas no subject.) - Correct:
I met a programmer who writes amazing code.(whois the subject ofwrites.) - Incorrect:
The device controls the system needs an update.(The verbcontrolshas no subject.) - Correct:
The device that controls the system needs an update.(thatis the subject ofcontrols.)
- 1Using
whichfor People orwhofor Things: Whilethatis versatile,whoandwhichhave distinct domains. Mixing them demonstrates a fundamental misunderstanding of their application.
- Incorrect:
The scientist which developed the vaccine received an award.(scientistis a person.) - Correct:
The scientist who developed the vaccine received an award. - Incorrect:
The experiment who failed was repeated.(experimentis a thing.) - Correct:
The experiment which failed was repeated.
- 1Adding a Redundant Subject Pronoun: Once the relative pronoun acts as the subject, introducing an additional pronoun (e.g.,
he,she,it,they) in the same clause is superfluous and creates an ungrammatical structure. The relative pronoun has already fulfilled the subject role.
- Incorrect:
The colleague who she presented the proposal is very persuasive.(whois already the subject ofpresented.) - Correct:
The colleague who presented the proposal is very persuasive. - Incorrect:
The report which it details the findings is quite long.(whichis already the subject ofdetails.) - Correct:
The report which details the findings is quite long.
- 1Subject-Verb Agreement Errors: The verb in the relative clause must agree with the antecedent, not the relative pronoun itself. This can be tricky, especially with phrases like
one of the...
- Incorrect:
He is one of those students who always asks insightful questions.(whorefers tostudents, plural, notone.) - Correct:
He is one of those students who always ask insightful questions. - Incorrect:
It was the only project that were approved by the committee.(thatrefers toproject, singular.) - Correct:
It was the only project that was approved by the committee.
Real Conversations
Subject relative pronouns are ubiquitous in authentic English communication, making sentences more efficient and nuanced across various contexts, from informal text messages to professional discussions. Their natural integration demonstrates a speaker's ability to connect ideas smoothly, avoiding the choppy effect of multiple simple sentences.
- Workplace Communication (Email/Meeting):
- 'Could you follow up with the client who called this morning regarding the new proposal?' (More efficient than: 'The client called this morning regarding the new proposal. Could you follow up with them?')
- 'The project timeline which was circulated earlier requires some adjustments.' (Clearer than: 'The project timeline was circulated earlier. It requires some adjustments.')
- Casual Social Interaction (Texting/Chat):
- 'Did you see that new movie that everyone's talking about?' (A common, natural phrasing for recommendations.)
- 'I'm meeting up with a friend who just got back from studying abroad.' (Provides context about the friend simply.)
- Academic Discussion/Presentations:
- 'Researchers are exploring new technologies which could revolutionize renewable energy.' (Concise way to describe specific technological advancements.)
- 'The theory that underpins this entire field was first proposed in the 1950s.' (Clearly identifies the foundational theory.)
These examples illustrate how subject relative pronouns allow speakers to embed descriptive information directly where it's most relevant, creating a more cohesive and sophisticated flow of ideas. Native speakers instinctively use these structures to maintain a natural pace and level of detail in their communication. The choice between who, which, and that often subtly reflects the formality of the context, with that being very common in casual speech and writing, while who and which may lend a slightly more formal or precise tone.
Quick FAQ
that always replace who or which when they are subjects?Choosing the Correct Subject Relative Pronoun
| Antecedent (The Noun) | Relative Pronoun | Function | Example |
|---|---|---|---|
|
People (Formal)
|
Who
|
Subject
|
The man who knows...
|
|
People (Informal)
|
That
|
Subject
|
The girl that lives...
|
|
Things/Animals
|
Which
|
Subject
|
The cat which barks...
|
|
Things/Animals
|
That
|
Subject
|
The car that broke...
|
|
Possession
|
Whose
|
Subject/Determiner
|
The boy whose dog...
|
Meanings
A relative pronoun connects a main clause to a relative clause. When that pronoun is the subject of the relative clause, it provides essential information about the noun it follows.
Identifying People
Using 'who' or 'that' to specify exactly which person we are talking about.
“The woman who won the lottery is my aunt.”
“Students that study hard usually pass.”
Identifying Things
Using 'which' or 'that' to specify exactly which object or concept we are discussing.
“The car which crashed was red.”
“I bought a phone that has a great camera.”
Defining Essential Information
Providing information that is necessary to understand which specific noun is being referred to.
“I don't like movies that have sad endings.”
“Where is the key which opens this door?”
Reference Table
| Form | Structure | Example |
|---|---|---|
|
Affirmative (Person)
|
Noun + who + verb
|
The woman who works here.
|
|
Affirmative (Thing)
|
Noun + which + verb
|
The bus which arrives at 9.
|
|
Negative (Person)
|
Noun + who + auxiliary + not + verb
|
The man who doesn't smoke.
|
|
Negative (Thing)
|
Noun + that + auxiliary + not + verb
|
The app that doesn't work.
|
|
Question
|
Auxiliary + Noun + who + verb...?
|
Is she the girl who won?
|
|
Plural Nouns
|
Plural Noun + who/that + verb
|
The students who study hard.
|
|
With Prepositions
|
Noun + who + verb + preposition
|
The person who I work with.
|
|
Formal Thing
|
Noun + which + verb
|
The document which details the plan.
|
Formality Spectrum
There is a gentleman who is inquiring after you. (Workplace/Street)
There is a man who is looking for you. (Workplace/Street)
There's a guy that's looking for you. (Workplace/Street)
Some dude's lookin' for ya. (Workplace/Street)
The Relative Pronoun Bridge
People
- Who Subject
- That Informal Subject
Things
- Which Subject
- That Neutral Subject
Subject vs. Object Pronouns
Can I drop the pronoun?
Is there a verb immediately after the pronoun?
Is there a noun/pronoun after it?
Common Antecedents
People
- • The teacher
- • The pilot
- • The neighbor
Things
- • The package
- • The computer
- • The law
Examples by Level
The boy who is happy.
The car that is red.
A teacher who is nice.
A book that is big.
I know a girl who speaks English.
This is the phone that works well.
The man who lives here is old.
I like movies that are funny.
The company which produces these cars is Japanese.
People who want to join the club must pay a fee.
Is there a restaurant that serves vegetarian food?
The software which was installed yesterday is crashing.
The candidates who were interviewed yesterday were all excellent.
The law, which was passed last year, has caused many problems.
Anyone who believes that story is very gullible.
The evidence that was presented in court was convincing.
The factors which contribute to climate change are multifaceted.
It was my brother who eventually convinced me to move.
The individual who is found responsible will be prosecuted.
The theories that underpin this research are quite complex.
The nuances that characterize his later work are often overlooked.
He is a man who, despite his flaws, remains deeply respected.
The mechanisms which facilitate this biological process are still being studied.
Such are the challenges that await any newcomer to the field.
Easily Confused
Learners often use 'whom' as a subject because it sounds more formal.
Learners don't know when to use commas.
Using 'what' as a relative pronoun.
Common Mistakes
I have a friend lives in London.
I have a friend who lives in London.
The car is red is mine.
The car that is red is mine.
A person which works here.
A person who works here.
The man who he lives here.
The man who lives here.
The book who I bought.
The book that I bought.
Is this the bus goes to the city?
Is this the bus that goes to the city?
The people lives in this house.
The people who live in this house.
The man I met him was nice.
The man who I met was nice.
Everything what happened was my fault.
Everything that happened was my fault.
The lady who she called you is my boss.
The lady who called you is my boss.
The person whom called you is waiting.
The person who called you is waiting.
Sentence Patterns
I know a person who ___.
The ___ that ___ is ___.
Is there anything which ___?
Anyone who ___ must ___.
Real World Usage
The girl that lives next door is having a party.
I am a person who takes initiative.
I want to return the item which arrived damaged.
Take the bus that goes to the museum.
A traveler who loves coffee.
The party who signs this contract...
The Verb Test
No Double Subjects
That is Safe
Formal 'Which'
Smart Tips
Stop! You need a relative pronoun. Don't jump straight to the verb.
Use 'who' for people and 'which' for things. Avoid 'that' to sound more academic.
Try to replace the pronoun with 'He' or 'It'. If the sentence works, it's a subject!
Contract 'that is' to 'that's' and 'who is' to 'who's'. It sounds much more natural.
Pronunciation
Contraction of 'that is'
In spoken English, 'that' and 'is' are almost always contracted to 'that's'.
Weak form of 'who'
The 'h' in 'who' is often very soft, and the vowel becomes a schwa-like sound in fast speech.
Relative Clause Rise-Fall
The man who LIVES here (slight rise) is NICE (fall).
The rise on the relative clause indicates it is descriptive information.
Memorize It
Mnemonic
S.O.S. — Subject Or Stay! If the pronoun is the Subject, it must Stay.
Visual Association
Imagine a bridge connecting two islands. If the bridge (the pronoun) is missing, the cars (the verbs) fall into the water because they have no road (subject) to drive on.
Rhyme
If a verb comes next in line, keep the pronoun every time!
Story
A king (the noun) has a messenger (the relative pronoun) who carries a message (the verb). If the king sends the message without the messenger, the message never arrives. The messenger is the subject of the journey.
Word Web
Challenge
Look around the room. Describe 5 things using 'that' or 'which' followed by a verb (e.g., 'The lamp that sits on the desk'). Ensure you don't drop the pronoun!
Cultural Notes
British speakers are slightly more likely to use 'which' in defining relative clauses than American speakers, though 'that' is still dominant in speech.
American English strictly prefers 'that' for defining clauses and 'which' for non-defining clauses (with commas).
In some rural dialects, 'as' was historically used as a relative pronoun, though this is now very rare and considered non-standard.
Relative pronouns in English evolved from interrogative pronouns (who/which) and demonstrative pronouns (that) in Old English.
Conversation Starters
Tell me about a person who inspires you.
What kind of movies do you like?
Describe a piece of technology that you can't live without.
What are the qualities of a leader who succeeds?
Journal Prompts
Common Mistakes
Test Yourself
The man ___ lives next door is a doctor.
Find and fix the mistake:
The car is parked outside is mine.
I have a computer ___ works very fast.
Combine them using a relative pronoun.
'The book that is on the table is mine.'
Identify the 'Object' relative clause.
A: Which phone should I buy? B: Buy the one ___ has the best battery.
Match each item on the left with its pair on the right:
Score: /8
Practice Exercises
8 exercisesThe man ___ lives next door is a doctor.
Find and fix the mistake:
The car is parked outside is mine.
I have a computer ___ works very fast.
Combine them using a relative pronoun.
'The book that is on the table is mine.'
Identify the 'Object' relative clause.
A: Which phone should I buy? B: Buy the one ___ has the best battery.
1. A pilot... 2. A key... 3. A student...
Score: /8
Practice Bank
12 exercisesThe new phone ___ has a great camera is very expensive.
The doctor she helped me was very kind.
Arrange these words into a sentence:
Arrange these words into a sentence:
Combine these sentences:
Match the nouns with the correct relative pronoun:
Which sentence is correct?
The company ___ manufactures these parts is based in Germany.
I met a person was very kind.
Combine the sentences:
The documentary ___ explores space travel is fascinating.
Which sentence is grammatically correct?
Score: /12
FAQ (8)
No. In standard English, if the relative pronoun is the subject of the clause, it must be included. Dropping it makes the sentence ungrammatical.
'Who' is more formal and preferred in writing. 'That' is very common in spoken, informal English. Both are grammatically correct.
In 'The book I read,' 'I' is the subject. In 'The book that is red,' 'that' is the subject. You can only drop the pronoun if it's NOT the subject.
Yes, 'which' is used for objects, animals, and ideas. Never use 'which' for people.
This is a 'double subject' error. 'The man who he lives here' is wrong. 'Who' already does the job of 'he'.
Not for these 'defining' clauses. These clauses are essential to know which noun you are talking about, so no commas are used.
'Whose' is a possessive relative pronoun. It is followed by a noun, and together they can be the subject: 'The boy whose dog barked.'
In American English, 'that' is much more common for defining clauses. In British English, 'which' is used more often than in the US, but 'that' is still very frequent.
Scaffolded Practice
1
2
3
4
Mastery Progress
Needs Practice
Improving
Strong
Mastered
In Other Languages
que
English requires 'who' for people, whereas Spanish uses 'que' for both.
qui / que
In French, 'qui' is the subject pronoun regardless of whether it's a person or a thing.
der / die / das
German relative pronouns are much more complex due to case endings (nominative, accusative, etc.).
None (Pre-nominal modification)
Japanese has no words like 'who' or 'which' to connect clauses.
al-ladhi (الذي)
Arabic often requires a 'resumptive pronoun' later in the sentence, which English forbids.
de (的)
The word order is reversed compared to English.
Learning Path
Prerequisites
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