Abstract:

The evolution of grammar——tense, aspect and modality in bucheng is a typical caseof Chinese. Bucheng can be used as a modal word in the Tang Dynasty. Its grammaticalization is from a phrase to an adverb and a modal word. The change has reduced meaning to a grammatical one, and mis in turn brings more changes to its function in a sentence. Its evolution is interacted with other function words in the function word system. Its grammaticalization depends on the discourse situation. The gradual change is its grammaticalization's main mechanism.

Key words: modal word, bucheng, grammaticalization, mechanism