Grammaticalization of that-subordinators in English

It is generally held that some clause linkage markers have developed on the cline from parataxis through hypotaxis to subordination. As they have evolved from left to right on the cline, the discourse trategy on dependency of the interlocutors has increased. In this study, subordinations indicated by that will be illuminated intensively among others. The two that subordinators such as the complementizer that and the relativizer that originated from the same source, the deictic pronoun that. Their diachronic and synchronic similarities and differences will be diagnosed and compared in the synchronic grammars such as acoustics, phonetics, phonology, syntax, and usage-based corpus in which their historical changes are mirrored. And the mechanisms of grammaticalization will elaborate their differences (epistemic modality and emphasis) and similarities (focus shift and focus fortification) of discourse strategy on dependency.