Yes/No Questions
A yes/no question is any question that can be answered with yes or no. To form one, you invert the subject and an auxiliary verb — that is, you move the auxiliary in front of the subject.
The most common auxiliaries used in yes/no questions are: be, do/does/did, have/has/had, can, could, will, would, should, might, and must.
The basic structure: Auxiliary + Subject + Main Verb + …?
Are you a student? Is she working today? Do they speak French? Does he live in the city? Did you see that film? Have you ever been to Japan? Can she drive? Would you like some tea? Should we leave now?
When the sentence has no auxiliary verb (simple present and simple past), you must add the "dummy" auxiliary do, does, or did. The main verb stays in its base form.
Statement: She plays tennis every week. Question: Does she play tennis every week? Statement: They finished the project. Question: Did they finish the project?
Never use "does" or "did" with another auxiliary. You would never say "Does she can swim?" — the correct form is simply "Can she swim?"
With the verb to be in simple tenses, no auxiliary is needed — be itself inverts with the subject:
He is tired. → Is he tired? They were happy. → Were they happy?
Wh- Questions
Wh- questions ask for specific information rather than a simple yes or no. They begin with a question word such as who, what, where, when, why, how, which, or whose. The structure is:
Question word + Auxiliary + Subject + Main Verb + …?
In other words, after the question word you use exactly the same inversion as in a yes/no question.
Where do you work? What does she want? When did they arrive? Why is he upset? How long have you been waiting? Which bus goes to the station? Whose bag is this?
How often combines with adjectives or adverbs to ask about degree, frequency, or quantity:
How often do you exercise? How far is the nearest hospital? How much does it cost? How many people were there? How long will the journey take?
Notice that the auxiliary and subject still invert after any of these combinations. The question word (or phrase) simply moves to the very front.
When asking about a prepositional phrase, the preposition can go at the end in natural spoken English: "Who are you talking to?" or, more formally, "To whom are you talking?" Both are correct; the first is far more common in everyday speech.
With how come (informal, meaning "why"), no inversion is used — the word order stays the same as in a statement:
How come you didn't call me? (not: How come didn't you call me?) How come she knows about it?
Subject vs. Object Questions
This is one area that confuses many learners, so pay close attention. The key distinction is: are you asking about the subject or the object of the verb?
Object questions follow the normal wh- question pattern (question word + auxiliary + subject + verb):
What did Sarah buy? (Sarah is the subject; what = the object she bought) Who did you call? (you = subject; who = the person you called) Which film did they see? (they = subject; which film = the object)
Subject questions are different. When the question word itself is the subject of the verb, you do not use an auxiliary and you do not invert. The word order looks just like a statement.
Who called you? (who = the subject doing the calling) What happened next? (what = the subject of happened) Which bus goes downtown? (which bus = the subject) Who invented the telephone? (who = the subject of invented)
A useful test: try replacing the question word with he, she, it, or they. If the sentence still makes sense without an auxiliary, it is a subject question.
Subject: Who broke the window? → She broke the window. ✓ (no auxiliary needed) Object: What did she break? → She broke it. ✓ (auxiliary needed in the question)
In subject questions with the simple present and simple past, there is no "do/does/did". Saying "Who did call you?" (when asking about the subject) is incorrect; the correct form is simply "Who called you?"
Tag Questions
A tag question is a short question added to the end of a statement. We use tag questions to check information, seek agreement, or invite the listener to respond. The rule for forming them has two parts:
- If the main clause is positive, the tag is negative.
- If the main clause is negative, the tag is positive.
The tag always uses the same auxiliary (or form of be) as the main clause, and it uses a pronoun, not a noun.
You are coming to the party, aren't you? She can swim, can't she? They have left already, haven't they? He finished the report, didn't he? It was a great concert, wasn't it?
You haven't met her before, have you? He doesn't like coffee, does he? They won't be late, will they? She can't drive, can she?
A few special cases are worth memorizing:
- "I am right, aren't I?" — amn't I is non-standard; aren't I is the accepted form in most varieties of English.
- "Let's go, shall we?" — imperatives with let's use shall we.
- "Open the window, will you? / would you? / won't you?" — direct imperatives take will you, would you, or won't you.
Intonation matters. A falling intonation on the tag signals that you expect agreement ("Nice day, isn't it?↘"). A rising intonation signals a genuine question where you are less sure of the answer ("You've been here before, haven't you?↗").
Indirect Questions
Indirect questions are questions embedded inside a polite phrase or another clause. They are softer and more formal than direct questions, and they are extremely common in professional and academic contexts.
The key rule: inside an indirect question, use normal statement word order (subject + verb), not the inverted order of a direct question. You also drop the auxiliary do/does/did in simple tenses.
Common introductory phrases include: Could you tell me …, Do you know …, I was wondering …, Can you explain …, Would you mind telling me …
Direct: Where does she work? Indirect: Could you tell me where she works? Direct: What time does the train leave? Indirect: Do you know what time the train leaves? Direct: Why did he leave early? Indirect: I was wondering why he left early. Direct: How long will it take? Indirect: Can you tell me how long it will take?
For yes/no indirect questions, use if or whether to introduce the embedded clause:
Direct: Is the office open? Indirect: Do you know if the office is open? Direct: Did she get the job? Indirect: I'd like to know whether she got the job. Direct: Can you help me? Indirect: I was wondering if you could help me.
Notice that indirect questions often end with a full stop (period), not a question mark — especially when the main clause is a statement: "I was wondering whether you had time." A question mark is used when the main clause is itself a question: "Could you tell me where the exit is?"
Common Mistakes to Avoid
Even advanced learners make predictable errors with question formation. Here are the most frequent ones — with corrections.
1. Forgetting to invert in direct questions
✗ You are ready? ✓ Are you ready? ✗ She can come? ✓ Can she come?
2. Using "do/does/did" with another auxiliary
✗ Does she can drive? ✓ Can she drive? ✗ Did you must leave? ✓ Did you have to leave?
3. Adding "do/does/did" in subject questions
✗ Who did call you? ✓ Who called you? ✗ What did happen? ✓ What happened?
4. Using inverted word order inside indirect questions
✗ Can you tell me where does she live? ✓ Can you tell me where she lives? ✗ I don't know what did he say. ✓ I don't know what he said.
5. Wrong tag question polarity or auxiliary
✗ She is coming, isn't she? → ✓ (this is actually correct) ✗ He finished it, didn't he? → ✓ (this is also correct) ✗ They have a car, don't they? → ✗ when "have" = possess ✓ They have a car, haven't they? (British English) ✓ They have a car, don't they? (American English — both accepted)
6. Forgetting "if" or "whether" in indirect yes/no questions
✗ Do you know the meeting has started? ✓ Do you know if the meeting has started? ✓ Do you know whether the meeting has started?
The single fastest fix for most question errors: ask yourself, "Have I moved an auxiliary in front of the subject?" For direct questions, the answer should almost always be yes. For indirect questions, the answer should always be no — keep normal word order after the introductory phrase.
Frequently Asked Questions
What is the difference between a wh- question and a yes/no question?
A yes/no question can be answered with simply 'yes' or 'no' (e.g., 'Do you speak English?'). A wh- question asks for specific information and begins with a question word such as who, what, where, when, why, or how (e.g., 'Where do you work?').
Why do some questions not use 'do' or 'does'?
You only need 'do/does/did' when the verb in the sentence has no auxiliary. If the sentence already contains an auxiliary (can, will, have, be, etc.), you simply move that auxiliary in front of the subject. Also, in subject questions — where the question word itself is the subject — no auxiliary is added at all (e.g., 'Who called you?').
What is a subject question, and how do I form one?
A subject question asks about the subject of the verb. Because the question word is already the subject, you use the same word order as a statement — no inversion and no 'do/does/did'. For example: 'Who broke the window?' (not 'Who did break the window?').
How do I form a tag question?
Use the same auxiliary as in the main clause, then add a pronoun. If the main clause is positive, the tag is negative (e.g., 'She can swim, can't she?'). If the main clause is negative, the tag is positive (e.g., 'He doesn't know, does he?').
What is an indirect question and when should I use it?
An indirect question is a question embedded inside a polite phrase such as 'Could you tell me…' or 'Do you know…'. Use indirect questions to sound more polite or formal. Crucially, the word order inside the embedded clause is the same as in a statement — not inverted. For example: 'Could you tell me where the library is?' (not 'Could you tell me where is the library?').
Can I end an indirect question with a question mark?
It depends on the main clause. If the introductory phrase is itself a question (e.g., 'Could you tell me…?'), use a question mark. If the main clause is a statement (e.g., 'I was wondering whether…'), end with a full stop (period).