urgent!

[gio]

'only after everyone has arrived will we serve the food'. Please tell me that this sentence is wrong! If not, why does the auxiliary verb is before the pronoun in an affirmative sentence? Does it give emphasis?
and one more
'Can you tell me what time the last train leaves?'. why we don't say 'can you tell me what time does the last bus leave?'.

[Tdol]

In the first case, we invert the second verb when the sentence starts with 'only', just as we invert the verbs if a sentence starts with never/seldom, etc. The idea behind it is to give some emphasis or focus. In the second case, you are only asking one question and that is 'can you tell me...', so the rest shouldn't take the word order of a question- it's an embedded question.

[gio]

Hi!
Thank you very much for elucidating me. You really helped me.
thank you again.
regards Gio

[Tdol]

You're welcome, Gio.