Grammar · Questions & Negation
Subject vs Object Questions
Who built Baymax? Who did Baymax help? Two questions, two word orders, with the film Big Hero 6.
Grammar › Questions & Negation › Subject vs Object Questions
The rule in one sentenceWhen the question word is the subject (the person who does the action), keep normal word order and use no do / does / did (Who built Baymax?). When the question word is the object (the person or thing that receives the action), add do / does / did before the subject (Who did Baymax help?).
About the film
Big Hero 6 is a Disney film from 2014. Hiro is a fourteen-year-old boy who is very good at building robots. He lives in a city called San Fransokyo with his aunt and his older brother, Tadashi. Tadashi builds Baymax, a big, soft, white robot. Baymax is a healthcare robot: his job is to help people who are hurt or sick. After a sad accident, Hiro and Baymax find some new friends, and together they become a team of superheroes. The film won the Oscar for Best Animated Feature.
What does it do?
Most questions in English need a helper verb: do, does or did. But some questions do not. The difference is the job of the question word.
In a subject question, the question word is the person or thing that does the action. In an object question, the question word is the person or thing that receives the action.
Here is an easy test. Answer the question with a name or a thing. If the answer keeps the same word order as the question, it is a subject question. Who built Baymax? → Tadashi built Baymax. Same order, so no helper verb.
In speech, the helper verb and the question word often join together in the negative. Short forms only change the helper, never the main verb:
Who built Baymax? Who did Baymax help?
Same question word, same robot. In the first question, “who” is the builder. In the second, “who” is the person that Baymax helped.
Visual guide
Teacher Teddy’s illustrated guide to this rule is being drawn — the full swipe-through infographic will appear here soon.
How to make it
Subject question — no helper verb
Who built Baymax?
Tadashi built Baymax.What happened at the science fair?
A fire happened at the science fair.Which friend wears a monster suit?
Fred wears a monster suit.Object question — helper + subject + verb
Who did Baymax help?
Baymax helped Hiro.What does Hiro build?
Hiro builds tiny robots.Which robot does Hiro love most?
Hiro loves Baymax most.In a subject question, the question word takes the place of the subject, and the verb comes next, just like in a normal sentence. In an object question, the helper shows the time: do / does for the present, did for the past. The main verb stays in its base form.
When to use each one
Subject question
Object question
Words that help: subject or object?
Look at the words after the question word. If a new subject comes next, you need a helper verb.
Subject question → a verb comes next
Object question → a helper and a subject come next
Common mistakes
❌ Who did build Baymax?
✅ Who built Baymax?
“Who” is the builder, so it is the subject. No helper verb.
❌ What Hiro invented at the science fair?
✅ What did Hiro invent at the science fair?
Hiro is the subject and “what” is the thing he made. Object questions need “did”.
❌ Who does helps sick people?
✅ Who helps sick people?
Never use a helper verb and a verb with -s together. Subject question: just the verb.
❌ Who did Baymax helped?
✅ Who did Baymax help?
After “did”, the main verb goes back to its base form: help, not helped.
One more thing
This part is a little harder. You can come back to it later.
“Whom” is the old object form of “who”.
✅ Whom did Baymax help? is correct, but it sounds very formal today. In everyday English, people say Who did Baymax help?
✅ Short answers to a subject question can use the helper again: Who built Baymax? — Tadashi did.
Practice: subject or object question?
Eight questions. Choose one answer. You get the answer, and why.
1. Who ___ Baymax?
“Who” is the builder → subject question, no helper.
2. What ___ Hiro invent?
Hiro is the subject → object question, add “did”.
3. What ___ at the science fair?
“What” is the thing that happened → subject question.
4. Who ___ Baymax help?
Baymax is the subject → object question: does + base verb.
5. Which friend ___ a monster suit?
“Which friend” is the one wearing it → subject question.
6. Which film ___ you like best?
“You” is the subject → object question, add “do”.
7. How many friends ___ the team?
The friends are the ones joining → subject question.
8. Who ___ Hiro live with?
Hiro is the subject → object question: does + live.
Your turn
Choose one ending. Then listen to your sentence.
Every sentence here is correct. Pick the one that is true for you. Say it out loud too!
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