Subject and Object Questions
If the question word (who/what) is the one doing the action, keep normal statement word order with no do/does/did ("Who broke it?"); if it's receiving the action, add do-support and invert the subject and auxiliary ("Who did you see?").
Formula
Examples
Usage
- •Asking who or what performed the action, when the question word replaces the subject
- •Asking who or what received the action or was affected by it, when the question word replaces the object
- •Clarifying information you didn't catch ("Someone called." "Who called?")
- •Everyday questions about people, causes, or events without needing do-support
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Try 5 cards free — no signup →Do you need "do" after who or what?
Only if the question word is the object of the sentence, not the subject. When who/what replaces the subject — the one performing the action — no do/does/did is added, and word order stays exactly like a statement: "Who broke the window?" (compare: "Tom broke the window.") When who/what replaces the object, ordinary do-support and inversion apply: "Who did you see?" (compare: "You saw Tom.")
How do you tell a subject question from an object question?
Test it by dropping a name straight into the blank left by the question word: "___ broke it" → "Tom broke it" works, so it's a subject question with no auxiliary needed. If the question word is instead standing in for the object, the sentence needs the normal question machinery: auxiliary + subject + base verb.
Who broke it vs who did you see — what's the difference?
"Who broke it?" asks who performed the breaking — who is the subject, so the verb stays in its normal statement form (broke). "Who did you see?" asks who received the seeing — who is the object, you is the subject, so did + inversion is required.
Comparison Table
| Form | Word order | Example |
|---|---|---|
| Subject question | Question word + verb, no auxiliary | Who broke the window? |
| Object question | Question word + do/does/did + subject + base verb | Who did you see at the party? |
Save this comparison chart
More Examples
Who broke the window?
Subject question — 'Who' is the person who did the breaking; no auxiliary needed.
Who did you see at the party?
Object question — 'you' is the subject, so 'did' + inversion is required.
What happened to your car?
Subject question, past simple — 'What' is the subject of 'happened', not 'did what happen'.
What did you buy at the store?
Object question, past simple — normal question order with 'did'.
Who is calling you every day?
Subject question, present continuous — 'is' is the ordinary auxiliary of the tense, not extra do-support; word order stays statement-like.
Who does she visit on Sundays?
Object question, present simple — 'she' is the subject, so 'does' + inversion is needed.
Common Mistakes
- ✗Adding an unnecessary auxiliary to a subject question: "Who does broke it?" instead of "Who broke it?"
- ✗Forgetting the auxiliary in an object question: "Who you saw?" instead of "Who did you see?"
- ✗Wrong word order in object questions: "Who did see you?" instead of "Who did you see?"
- ✗Using a plural verb after Who/What even when the answer is plural: say "Who wants ice cream?" not "Who want ice cream?" — the verb agrees with 'Who' as singular.
Tips
- ✓Test: can you answer by dropping a name straight into the blank ("___ broke it" → "Tom broke it")? If yes, it's a subject question — no do/does/did.
- ✓If the question word is not the one doing the action, build the sentence like a normal question: auxiliary + subject + verb.
- ✓Subject questions keep statement word order — that's the giveaway they don't need 'do/does/did'.
Advanced Notes
Native speakers rely on this distinction instinctively, but learners often over-apply do-support out of habit, producing errors like "Who does live here?" Subject questions are extremely common in spoken English for quick clarification ("Someone's at the door." "Who is it?") precisely because they need no extra machinery — you just swap the subject for a question word. Formal written English occasionally uses "whom" for object questions ("Whom did you invite?"), but in everyday speech "who" covers both roles, and the auxiliary + inversion pattern alone signals that it's functioning as an object question.
FAQ
Why is "Who does broke it?" wrong?
"Who" is the subject of "broke" here — it's the one doing the breaking — so no auxiliary is needed at all. Adding "does" is unnecessary do-support; the correct question is simply "Who broke it?"
Why is "Who you saw?" wrong — don't I need do-support?
Yes — here "who" is the object (the person seen), and "you" is the subject, so the question needs an auxiliary and inversion: "Who did you see?" Dropping "did" leaves the sentence in statement word order, which isn't a valid object question.
How do I know if it's a subject or object question?
Try dropping a name into the blank where the question word is: if it reads like a normal statement ("___ broke it" → "Tom broke it"), it's a subject question — no do/does/did. If the question word instead fills the object slot, you need the standard auxiliary + subject + verb pattern.
"Who wants ice cream" or "who want ice cream" — which is correct?
"Who wants ice cream?" — the verb agrees with "who" as singular, regardless of how many people the real answer turns out to include.
Is "whom" the same as "who" in object questions?
They serve the same role, but "whom" is the more formal, traditionally "correct" object form used mainly in careful writing: "Whom did you invite?" In everyday speech, "who" covers both subject and object questions, and the auxiliary + inversion pattern alone signals that it's functioning as an object question.
What are subject and object questions?
A subject question asks who or what performed the action, and keeps normal statement word order with no do/does/did: "Who broke it?" An object question asks who or what received the action, and needs an auxiliary plus inversion: "Who did you see?" The same question word (who/what) forms either type, depending on which role it's filling.
Practice
- 1.Who (break) the window?
- 2.Who you see at the party?
- 3.What to your car?
- 4.What you buy at the store?
- 5.Who she visit on Sundays?
Compare With
Other B1 Topics
Present Perfect
Used for past actions that still matter or connect to now
Present Perfect Continuous
Used for ongoing actions that started in the past and still continue
Modal Verbs
Expresses ability, obligation, permission, or possibility
Passive Voice (Basic)
Used for sentences where the action or result matters more than who did it
Used To
Used for past habits or states that no longer exist
Future Continuous
Used for actions in progress at a specific future moment
Question Tags
Used for confirming information or seeking agreement at the end of a statement
Linking Words: However, Although, Despite, In Spite Of
Used for connecting contrasting ideas using concession and contrast markers
Relative Clauses (Defining)
Clauses that identify exactly which person, thing, or place you mean.
So and Such
Use so before adjectives/adverbs and such before nouns to emphasize degree, often followed by a that-clause showing the result.
Order of Adjectives
The fixed order adjectives usually follow before a noun: opinion, size, age, shape, colour, origin, material, purpose.
Future Time Clauses
Use present simple, not will, after when/as soon as/before/after/until/once even when the meaning is future.