Quick answer. In a subject question, who or what performs the action, so Present/Past Simple does not use do, does or did: Who called you? In an object question, someone else performs the action, so the usual question auxiliary returns: Who did you call?
- identify the missing subject or object;
- choose whether an auxiliary is needed;
- build questions in several tenses;
- handle be, prepositions and negative questions.
Subject question or object question?
| Question type | Pattern | Example | Answer |
|---|---|---|---|
| subject | who/what + verb | Who broke the window? | Tom broke it. |
| object | who/what + auxiliary + subject + verb | What did Tom break? | He broke the window. |
| subject with be | who/what + be + complement | Who is ready? | Maya is ready. |
| object after a preposition | who + auxiliary + subject + verb + preposition | Who are you waiting for? | I’m waiting for Leo. |
Use the expected answer as a diagnostic. If the answer replaces the person or thing before the verb, the question word is the subject. If the answer comes after the verb, the question word is the object.
Exercise 1: label S or O
- Who opened the door?
- Who did you invite?
- What happened after lunch?
- What did she buy?
- Who knows the answer?
- Who does Anna know here?
Answers to Exercise 1
- S
- O
- S
- O
- S
- O
Questions 1, 3 and 5 have no separate subject after the question word. Questions 2, 4 and 6 name the subject after the auxiliary.
Exercise 2: add an auxiliary only when needed
- Who ___ wrote this message?
- Who ___ she write to yesterday?
- What ___ caused the delay?
- What ___ they discuss at the meeting?
- Who ___ lives next door?
- Who ___ your brother call every week?
Answers and explanations
- —: Who wrote this message?
- did
- —: What caused the delay?
- did
- —: Who lives next door?
- does
Do not add did to a subject question in the Past Simple. The main verb itself carries the past form: Who wrote…?
Questions in different tenses
| Tense | Subject question | Object question |
|---|---|---|
| Present Simple | Who teaches this class? | Who does Maya teach? |
| Past Simple | Who sent the file? | Who did Maya send the file to? |
| Present Continuous | Who is using the room? | What is Maya using? |
| Present Perfect | Who has finished? | What has Maya finished? |
| Modal verb | Who can help? | Who can Maya help? |
With Continuous, Perfect and modal forms, both question types already contain an auxiliary. The key difference remains the position of the named subject, not simply whether an auxiliary appears.
Exercise 3: build both questions
Use the statement Olivia sent Mark an email yesterday.
- Ask about Olivia.
- Ask about Mark.
- Ask about the email.
- Ask about the time.
Model questions
- Who sent Mark an email yesterday?
- Who did Olivia send an email to yesterday?
- What did Olivia send Mark yesterday?
- When did Olivia send Mark an email?
Only the first question asks for the subject. The other three keep Olivia as the grammatical subject.
Exercise 4: correct the mistake
- Who did call you last night?
- What happened it yesterday?
- Who you invited to the party?
- Who does works in this office?
- What she is reading?
- Who did you speak yesterday?
Corrections
- Who called you last night?
- What happened yesterday?
- Who did you invite to the party?
- Who works in this office?
- What is she reading?
- Who did you speak to yesterday?
Prepositions in object questions
In neutral spoken English, the preposition often stays at the end: Who are you talking to? A more formal version can place it first: To whom are you talking? Do not delete a preposition required by the verb. Practise related patterns in prepositions exercises and phrasal verbs exercises.
Exercise 5: translate into English
- Кто разбил чашку?
- Какую чашку ты разбил?
- Кто сейчас говорит?
- С кем она разговаривает?
- Что изменилось?
- Что они изменили?
Model translations
- Who broke the cup?
- Which cup did you break?
- Who is speaking now?
- Who is she talking to?
- What changed?
- What did they change?
Typical mistakes for Russian-speaking learners
- Adding do/does/did to every question.
- Keeping an extra pronoun after a subject question:
Who called he? - Forgetting the third-person -s: Who works here?
- Removing the final preposition from an object question.
- Assuming that every question with an auxiliary is an object question.
Self-check
Thirty-second test
Turn Alex helped Nina into two questions. The answers are Who helped Nina? and Who did Alex help? If you can explain why only the second uses did, you have identified the grammatical roles rather than memorised a word order.
Related practice
Continue with question tags, indirect questions, mixed tenses, Past Simple, the tenses test, modal verbs and relative clauses.
