Punctuation
Question mark
Question mark
Direct question
The question mark is used after a direct question.
At what time does the game begin?
Indirect question
The question mark is not used after an indirect question.
Sally would like to know why it took so long to reply to her letter.
Polite request
The question mark is not used after a polite request that sounds like a question.
It is, after all, a request, not a question. Therefore, a period is used.
Would you please pass me the stapler.