Interjections are elements that conventionally constitute utterances by themselves and express a speaker’s mental state or his or her reaction towards an element in the linguistic or extralinguistic context. In Chinese, and presumably other languages, interjections constitute a special class of words, which differ from other word categories syntactically, semantically, as well as phonetically (Poggi 2009).

Syntactically, interjections do not enter into specific syntactic relations with other elements; they are always used independently, acting as a s…