1. A whole idea can be an object
In I know the answer, the object names the answer. In I know where the meeting is, the object is a whole subordinate clause identifying the information I know. After wonder, it identifies the issue I am thinking about; after explain, what is explained; after discuss, the subject of discussion.
These clauses are often called indirect or embedded questions. They do not necessarily report someone’s words: We need to establish who approved the change can introduce an unresolved question for the first time.
verb + wh-clause
- verb / V —
- A word for an action or state, such as work or be. The pattern determines its form.
- clause —
- A construction with a verb, often with its own subject: when I arrived. A non-finite clause may leave the subject unspoken: to get home.
We need to establish who approved the change.
We need to establish who approved the change.
The whole clause who approved the change identifies the information that needs to be established.
The report explains how the figures were calculated.
The report explains how the figures were calculated.
What is being explained is the method of calculation, not the figures themselves.
2. Statement word order inside the clause
In standard written English, a wh-word is followed by the subject and then the verb: where the files are, why the plan failed, how we can help. Question inversion in a main clause is not carried into the subordinate clause.
Question-forming do, does or did disappears, and the main verb takes the appropriate form: Where does she work? → I wonder where she works. However, do is not banned altogether: in why she did not reply, it forms a negative; in what she does, it is the main verb; in what she DOES know, it may add emphasis.
wh-word + subject + verb, or auxiliary + main verb
- subject / S —
- The grammatical subject: who or what the clause is about; the verb agrees with it. In The book was written, the book is the subject, although someone else does the action.
- verb / V —
- A word for an action or state, such as work or be. The pattern determines its form.
- auxiliary —
- A helping verb used to form tenses, questions or negatives: do, have, be.
Nobody understands why the door has been locked.
Nobody understands why the door has been locked.
The subject the door comes before the entire verb sequence has been locked.
Please explain why the payment did not arrive.
Please explain why the payment did not arrive.
Did remains to form the negative. After did not, use arrive, not arrived.
3. When who or what is itself the subject
In Who arrived first?, who already occupies the subject position. Therefore I know who arrived first needs no additional subject or rearrangement. The same applies to which + noun when that phrase names the performer of the action.
Compare who contacted Maya with who Maya contacted. In the first, we are identifying the person who contacted Maya; in the second, Maya contacted someone. Statement word order does not mean there must be a separate noun subject after every wh-word.
Can you tell me which team won?
Can you tell me which team won?
Which team is the subject and is followed directly by won.
I cannot remember who Lina invited.
I cannot remember who Lina invited.
Lina is the subject; who identifies the person invited.
4. The wh-word selects the information, not a fixed verb partner
Why focuses on a reason, how on a method or process, where on a place, and when on a time. What asks about a thing, action or content; which identifies a choice from a set; how much and how many ask about an amount or quantity.
Do not memorize fixed pairings such as consider = whether or explain = why. You can consider why a plan failed, how to improve it or whether it is worth repeating. The choice depends on the intended meaning. At the same time, not every verb accepts every complement type: wonder whether naturally expresses uncertainty, while establish whether describes finding out a fact.
We discussed why attendance had fallen and how we could improve it.
We discussed why attendance had fallen and how we could improve it.
Both clauses depend on discussed, but identify different questions.
Please check how many seats are still available.
Please check how many seats are still available.
How many seats is a complete question phrase and also the subject of the subordinate clause.
5. Whether and if: an open yes/no question, not a condition
A yes/no question often requires whether or if: I wonder whether/if the office is open. Both are possible in this position. If does not become incorrect merely because the level is C1 or the context is business writing. Whether is particularly useful for explicitly stated alternatives.
Distinguish I do not know if they will call, which expresses uncertainty about a call, from I will wait if they call, where the call is a condition for waiting. After know, the clause identifies unknown information; after wait in the second example, it sets a condition.
In standard writing, choose whether or not when or not immediately follows the conjunction. With or not at the end, both are possible: I wonder if/whether they will agree or not. Whether to sign is also possible, but if to sign is not. Reduced infinitive clauses are a related boundary topic here, not a replacement for every full clause.
Please confirm whether or not the venue is accessible.
Please confirm whether or not the venue is accessible.
Or not immediately follows whether, a natural pattern in writing.
I wonder if we can reschedule the visit.
I wonder if we can reschedule the visit.
If introduces an unresolved question, not a condition for a future action.
6. The whole sentence can be a question
I know where the entrance is. is a statement. Do you know where the entrance is? asks the listener a question. In the second sentence, inversion is outside the embedded clause: Do you know. The embedded part where the entrance is does not change.
The form and function of the whole sentence determine the question mark, not the presence of a wh-word alone. Could you explain why the room is closed? correctly ends in a question mark. Please explain why the room is closed. is a request in imperative form.
Could you tell me where I should wait?
Could you tell me where I should wait?
Could you is inversion in the main question; I should is statement word order inside the embedded clause.
I wonder when the results will be published.
I wonder when the results will be published.
This is a statement about something unknown, not a sentence formed as a direct question.
7. That, wh-words and the meaning of what
Explain that the system failed is a grammatical report of the failure itself. Explain why the system failed concerns the reason. Explain how the system failed concerns the mechanism or process. Replacing why with that does not necessarily create a grammatical error, but may lose the intended meaning.
Not every what-clause is unambiguously a question. In Keep what you need, what means the thing or things that. In I wonder what you need, there is an unresolved question. I understand what you mean permits closely related readings: understanding the content of the message or understanding the answer to a question about the intended meaning. Context and function matter more than forcing a single syntactic label.
The manager explained that the schedule had changed.
The manager explained that the schedule had changed.
That introduces the fact being reported. The sentence is correct without why.
The manager explained why the schedule had changed.
The manager explained why the schedule had changed.
Why directs the explanation towards the reason for the change.
You may keep what you need.
You may keep what you need.
What you need refers to things, rather than a question to be answered.
8. Boundaries: register, tense and a practical check
Informal speech sometimes uses direct-question order inside a report, as in I asked where was the exit. This is a feature of conversational reporting. In standard written English, use I asked where the exit was.
Embedding alone does not require a past tense. I wonder where she lives concerns the present. When reporting an earlier conversation, tense and pronouns depend on the reporting context; do not shift them mechanically just because there is a subordinate clause.
Before sending an email, find the verb that takes the clause, establish which information is missing, and check the subject inside it. Then check the opening and final punctuation of the whole sentence separately.
We need to decide how we should respond.
We need to decide how we should respond.
The full clause explicitly names we. The reduced how to respond is also possible when the performer is clear.
Do you remember why we did not approve the design?
Do you remember why we did not approve the design?
The main sentence is a question with do; the embedded clause has the negative did not approve. Each auxiliary has its own role.
Common mistakes
Incorrect:I wonder she will accept the offer.
Correct:I wonder whether she will accept the offer.
To introduce an unresolved yes/no question after wonder, use whether or if. The bare clause she will accept cannot be attached here on its own.
Incorrect:Please explain why she did not replied.
Correct:Please explain why she did not reply.
Statement word order does not remove the negative auxiliary did not. It must be followed by the base form reply.
Incorrect:We need to find out where him works.
Correct:We need to find out where he works.
The subordinate clause needs the subject form he. Although the whole clause is the object of find out, its internal subject does not become the object form him.
Incorrect:I wonder who has took the keys.
Correct:I wonder who has taken the keys.
Who is the subject, so no second subject is needed. Has must be followed by the past participle taken. The order who has is itself correct.