Relationship Between Modal Sense Of English Modal Verb Must And Time, Aspect And Voice

English modal verbs are a complex semantic system. There exists gradience, ambiguity and merger in their semantic meaning. Semantic meaning of modal verbs is very sensitive to context. Different contextual factors have different influences on modal verbs. Time, aspect and voice which fall into important grammatical categories, constitute linguistic context of modal verbs. Meanwhile they have restriction on semantic meaning of modal verbs. Questions that how do time, aspect and voice influence semantic meaning of modal verbs and how much do they influence semantic meaning of modal verbs have been tough problems in linguistics which urgently need to be addressed. This thesis based on the theory and approach of Formal Concept Analysis studies the relationship between modal sense of English modal verb must and time, aspect and voice and their restriction on semantic meaning of modal verb must. It aims to discover relevant knowledge and provide valuable basis for the study of modal semantics and the study of natural language processing.A corpus with 2.1 million words is built. According to four authoritative dictionaries, four modal senses of must are classified. A training set and a testing set are constructed. Sixteen semantic features and eight syntactic features are extracted to form Formal Context of must, and then disambiguation model is generated. By inspection, self testing accuracy of the model of training set is 95.54% and that of testing set is 94.90%. The models are proved to be effective and can be used for further study. The accuracy of WSD of rules extracted from Formal Context is up to 92.36%.The relationship between modal sense of must and time, aspect and voice is made clear through forty-seven experiments. From the first to the sixteenth attributes are the MI of modal verb must and its adjacent word. From the seventeenth to the twenty-fourth attributes are syntactic features containing time, aspect and voice. The experiment finds out that the maximum influence on modal sense of must stems from retaining progressing aspect. Remaining one syntactic feature influences modal sense of must greatly. The MI of modal verb must and its adjacent word influences modal sense of must greatly, syntactic features together have a small influence and the MI of modal verb must and its adjacent word and syntactic features together constitute modal sense of must. In addition, unique attributes and unique composite attributes of the congeneric objects are discovered and collocation of time, aspect and voice and the MI of must are analyzed in structural partial-ordered attribute diagram. Negative attributes and affinity attributes of four senses are disposed of in structural partial-ordered object diagram. These findings provide valuable theoretical and practical basis for the study of semantics and the study of computational linguistics.