Blog about English
Understanding the difference between subject questions and object questions.
A subject question asks who or what performs the action, while an object question asks who or what receives or is affected by the action.
The grammatical role of the question word determines whether ordinary auxiliary inversion occurs.
When the question word is the subject of the clause, normal auxiliary inversion does not occur.
For example, Who called you? and What happened?
When the question word is the object of the clause, normal auxiliary inversion generally occurs.
For example, Who did you call? and What did she buy?
Who can be either the subject or object of a question, and the resulting word order changes accordingly.
Compare Who called John? with Who did John call?
What can function as the subject or object of a question, producing different sentence structures.
Compare What caused the problem? with What did you cause?
When the question word is the subject and be is the verb, the question normally retains subject-verb order.
For example, What is the problem? and Who is responsible?
When the question word asks about an object or complement, the normal question structure depends on the role of be.
For example, Who is she? asks for identification of the complement, while Who is she talking to? asks for an object of the preposition.
Subject questions in the present simple normally use the base or third-person singular form of the lexical verb without do-support.
For example, Who works here? and What causes this problem?
Object questions in the present simple normally use do or does before the subject.
For example, Who does she work with? and What does he want?
Subject questions in the past simple normally use the past form of the lexical verb without did.
For example, Who called you? and What caused the accident?
Object questions in the past simple normally use did before the subject and the base form of the lexical verb.
For example, Who did you call? and What did she buy?
When the question word is the subject, a modal remains with the verb phrase without ordinary inversion relative to the subject.
For example, Who can help us? and What might cause this reaction?
When the question word is the object, the modal normally occurs before the subject.
For example, Who can you help? and What should we do?
When the question word is the subject in a perfect construction, the auxiliary have remains before the past participle after the subject question word.
For example, Who has taken my keys? and What has caused the delay?
When the question word is the object in a perfect construction, have or has moves before the subject.
For example, Who has she invited? and What have they discovered?
When the question word is the subject of a progressive clause, be follows the subject question word without ordinary subject-auxiliary inversion.
For example, Who is coming? and What is causing the noise?
When the question word is the object, the progressive auxiliary be moves before the subject.
For example, Who are you waiting for? and What is she doing?
Existential structures can contain subject-like question words referring to the person or thing whose existence is being asked about.
For example, Who is there? and What is in the box?
When the question asks about an object within an existential construction, the auxiliary normally precedes there.
For example, What is there to eat? asks about available things in an existential structure.
Whom is the traditional object form of who and is mainly used in formal English, while who is standard and much more common in ordinary speech.
For example, Whom did you invite? is formal; Who did you invite? is normal in most everyday contexts.
When a person is the object of a preposition, ordinary English commonly leaves the preposition at the end of the question.
For example, Who are you talking to? and Who did she send the message to?
In formal English, the preposition can precede whom or another appropriate question phrase.
For example, To whom are you speaking? and With whom did she travel?
The verb in a subject question agrees with the understood number of the subject referred to by the question word.
For example, Who is coming? asks about one person or a group treated as singular, while Who are coming? can be used when the plurality of people is explicitly relevant.
Which can function as the subject when it selects an item from a known or limited set.
For example, Which caused the problem? and Which of these works best?
Which can function as the object when the speaker asks the listener to choose or identify an item from a set.
For example, Which did you choose? and Which one did she buy?
The difference between subject and object questions can change what information is requested even when the same question word is used.
Compare What caused the delay? with What did you cause?
Subject questions generally receive answers containing the requested person or thing directly, without repeating question-word syntax.
For example, Who called? John did, and Who broke the window? Sarah did.
Do can occur in a subject question for emphasis in marked constructions, even though ordinary subject questions do not require do-support.
For example, Who did call you? can be used when the speaker is emphasizing or challenging the expected answer.
When a verb has more than one object, the question word can target either object depending on the intended information.
For example, Who did she give the book to? asks about the recipient, while What did she give John? asks about the thing given.
In passive constructions, the grammatical subject may represent the original object, so identifying subject and semantic roles requires careful analysis.
For example, Who was invited? asks about the grammatical subject corresponding to the affected person.
An embedded clause can contain subject or object questions, and its question structure may differ from that of a direct question.
For example, I know who called and I know who she called illustrate subject and object roles inside embedded clauses.
If replacing the question word with a normal noun produces a sentence in which that noun is the subject, the question is a subject question.
For example, Who called John? corresponds to Sarah called John, so who is the subject.
If replacing the question word with a normal noun produces a sentence in which that noun is the object, the question is an object question.
For example, Who did John call? corresponds to John called Sarah, so who is the object.
The question word should be analyzed according to its grammatical role rather than its position or meaning alone.
This determines whether do-support and auxiliary inversion are required.
Use normal subject-question order when the question word is the subject and object-question inversion when it is the object.
Common mistakes include adding do to ordinary subject questions, omitting do from object questions, retaining a past form after did, and confusing who and whom.