I. Introduction
Intonation is “the use of suprasegmental phonetic features to convey post-lexical or sentence-level pragmatic meanings in a linguistically structured way[1]”. Speakers' right use of intonation can assist the listeners in processing the meaning of utterances quickly, otherwise listeners' recognition of speech will be delayed [2]. Therefore, it should be attached importance to in the second language (L2) acquisition, otherwise students may produce unnatural and even unintelligible speech.