Structurally, this type of question is identical to a statement. In speech, the sentence ends with a raised pitch. In writing, the sentence ends with a question mark. This type of question is used either to indicate doubt or to convey mild surprise.
ér zǐ ：mā ，wǒ xiǎng gēn péng yǒu qù yóu yǒng ，háng bú háng ？
Son: Mother, I have finished my homework; I want to go out with my friends.
mā mā ：nǐ gōng kè xiě wán le ？nǐ cái xiě le shí fèn zhōng ，jiù xiě wán le ？
Mother: You have fi nished your homework? You only spent ten minutes writing. (= doing your homework) and you already finished?
 Yip, P. C., Rimmington, D., Xiaoming, Z., & Henson, R. (2009). Basic Chinese: a grammar and workbook. Taylor & Francis.