No inversion is involved. Most polar questions lack overt marking, but are assumed to have been spoken with rising intonation. Evidence for this comes from Hall's (1944: 97)description: "When no specifically interrogative word or phrase is present, pitch rises to the highest point on the stressed syllable of the last word in the sentence." The Chinese A-not-A pattern is occasionally used, as in Can no can?
Source: Tong 1862: IV.55
Source: Tong 1862: VI.44