Is asking question with intonation grammatically correct? the context: had a discussion with colleague about the correct formal way to ask a question in English language. From all what i recall about grammar, seems that the formal way would be: "is that your mug?" However, the statement was made that: "that is your mug?" is grammatically correct, despite the fact that it is the statement and intonation can be used to indicate the question. So, is the latter grammatically correct in formal language?
There is a term for the non-inverted interrogative sentence: the declarative question. It is marked with a question mark in print and by intonation in speech. From Richard Nordquist at Grammar About.com:
A [declarative question is a] yes-no question that has the form of a declarative sentence but is spoken with rising intonation at the end.
Declarative sentences are commonly used in informal speech to express surprise or [to] ask for verification. The most likely response to a declarative question is agreement or confirmation.
example [in this case showing a pugnacious attitude rather than a casual enquiry]: "You think I'm kidding you? You think it's a joke to have to walk home on a clear night with an umbrella? You think that because I'm quirky I don't hurt? You've got it backwards. I'm quirky because I hurt." (Jack Weston as Danny in The Four Seasons, 1981)
I'd say they're much more appropriate in casual conversation or when about to hit someone than in formal writing. It's probably not helpful to argue about their grammaticality; this probably varies according to the grammarian.
Technically, I believe that it is grammatically correct but it is not the most formal way to ask or the best way.
There is a very common and idiomatic version of non-inverted interrogative sentence which occurs for the purpose of communicating incredulity or surprise. Usually the speaker is being ironic, sarcastic, sardonic, laconic or cynical and typically the words are spoken 'deadpan' (i.e. intonation does not rise at the end). There may well be, as well, intense eye contact. The reaction to such a question is often an outburst of emotional release (e.g. laughter or anger) -
"You just walked in without knocking?".