Do I have to add a question mark to a statement?

Question

When someone says "What would you like to discuss first?"

Should the reply be;

I would like to know how long does it take to process the request.

Or

I would like to know how long does it take to process the request?

I'm also confused about whether to add a question mark when I say the following:

He would like to know how long does it take to process the request.

Answer 1

In real English speech, interrogative sentences end with the voice shifting higher in pitch. The question mark symbolizes this.

When speaking, you can do this with anything, to indicate that you want confirmation or to know whether it is true or not. It implies the asker doesn't believe that what he/she is saying is true, or believes/hopes that what he/she doesn't apply to them.

I'm going to school? Yes, you are going. I don't care if you are sick.

Of course the proper question form is where subject and verb are reversed:

Am I going to school?

and where the auxillary verb do is used for negative questions.

Did he say that to me?

Sentences in question form require a question mark. If they are not in question form, then they don't require a question mark and don't require the voice pitch to be raised at the end of the sentence.

I wonder if he said that to me. (No question mark)

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When "questionifying" statements, because there's that implication that you don't believe the statement to be true or don't believe it to apply to you, it can come off as rude or ignorant.

I am working today? Yes, you're on the schedule. Quit playing around.

Answer 2

To be consistent, you can either:

• Format your embedded questions as questions:

I would like to know, "How long does it take to process the request?"
He would like to know, "How long does it take to process the request?"

• Or convert your embedded questions into embedded statements:

I would like to know how long it takes to process the request.
He would like to know how long it takes to process the request.

I have highlighted two differences.

• In the first sentence of each pair, I have highlighted the formatting for embedded questions, versus the absence of such formatting.
• In the second sentence of each pair, I have highlighted the question's do-support and the corresponding conjugation change.