In the current generative syntactic theory, syntactic elements of a language are classified into two categories: lexical and functional. In addition, it is also assumed that the structural representation of a sentence consists of three layers: CP (complementizer phrase), TP (Tense phrase)/IP (inflectional phrase) and DP (determiner phrase). This presents an interesting interface of theory and empirical data: the predictions of the theory help uncover generalizations regarding natural language; and the study of natural languages, in turn, contributes to universal grammar by enriching and modifying it.

This dissertation is a corpus-based synchronic and diachronic study of the Chinese complementizers (Cs). Specifically, it is on sentential adverbials, sentence-final mood particles and complementizers for the relative clause purpose. It uses the relevant generative theories including Chomsky's X-bar theory, Kayne's rigid X-bar scheme, Cinque's universal hierarchy of adverbs, and Rizzi's split CP to identify C elements in the sentence -initial, -final and -middle positions at the surface structure, to review their respective function, and to examine their respective distribution and relevant linear ordering in the CP tree when co-occurring. Since I follow Kayne's antisymmetry of syntactic linearization of the sentence structure, sentential adverbials, sentence-final mood particles and Cs in the sentence-middle position are all in the left periphery at the deep structure; hence this dissertation is a synchronic and diachronic study of the Chinese left periphery.

The dissertation also takes a historical perspective to explore the developmental steps of these C elements to trace their respective diachronic status in different historical stages of the Chinese language. It is found that the sentence-final mood particles in Modern and Classical Chinese are Cs for main clauses; de, zhi and yi are Cs for relative clauses, and zhi is de's previous form. As for Cs in the left periphery, speech act, evaluative, evidential and modal adverbials at the sentence level are qualified candidates. These findings provide insight on language universality and variation. The synchronic and diachronic linguistic evidence and the related analyses shed light on the developmental changes of the Cs throughout the history of the Chinese language.