Abstract
Abstract Utterance Final Particles have long been a topic for research. In this thesis, UFP a will be investigated by adopting the concept of speakers’ presuppositions in conversation. In addition, UFP a will be divided into two variants, namely, the high pitch (a1) and the low pitch (a2). There are two major differences between these two variants. For one thing, a1 mostly appears in the second part of one turn and is used by the second speaker in response to the first speaker’s knowledge state. For another thing, a2 is often placed in the first part of one turn and used by the first speaker to express the conflict between the existing events and his/her own knowledge state. During the research on the relation between UFP a and speakers’ knowledge state, it is found that speakers use UFP a not only to challenge the knowledge state behind assertions, but also to point out the gap between speakers’ knowledge states expressed implicitly in non-assertion utterances. By indicating such a gap, speakers can accomplish certain speech acts, such as challenge, warning, and so on. To sum up, the use of UFP a can help participants save time from pointing out explicitly the gap between their own knowledge states and the ones of the other side.