The grammatical sum does not form a coherent semantic identity. In the arrangement of the prefinal ending, the following elements add the grammatical and semantic meanings to the preceding elements. In conclusion, the arrangement of the prefinal ending of the estimation-confirmation is composed of the functions of estimation and confirmation and adds the semantic qualities of the information to the assumed element, and the confirmation-estimation undermines grammatical structure by less emphasizing the significance of confirmation. The ‘-리어-’ of the estimationconfirmation and the ‘-어리-’ of the confirmation-estimation have different syntactic structures, leading to different semantic qualities in terms of [±Confirmation]. This is accompanied by a change in the semantic elements of the estimation according to the meaning of the confirmation that precedes to or follows after the ‘-리-’, which is realized in the same form. Specifically, the form of estimation-confirmation carries the semantic element of simple assumption, while functioning to deliver the information. Therefore, the meaning unit of confirmation is not clearly distinguished. On the other hand, confirmation-estimation takes a form of rhetorical questionand therefore conveys the opposite meaning. It strengthens the role of confirmation, by placing the semantic element of the confirmation after the prefinal ending. The sentence of the confirmation-estimation often takes a form of “interrogative -려” (or “interrogative -리어-”) in front of the final ending. On the other hand, confirmation-estimation is associated with ‘-아- + -리 - + -아 (< 가)’. The grammatical arrangement and placement determines different semantic roles.BR If ‘-리-’ is realized in the form of estimation, it can be used to express the semantic differences determined byaccording to the order of arrangement. However, as a result, this research shows that ‘-리₁-’, which is settled in the form of estimation-confirmation, and ‘-리₂-’, is realized in a form of the confirmation-estimation, and the both are originally different grammatical elements. In a historical sense, there is no precedent to ‘-리₁-’ coming before the prefinal endings of ‘-거/어-아-’, except for ‘-리₂-’. ‘★’ and ‘★’ in Sǒktok kugyǒl during the Koryǒ period, which reveals the historical trajectory of the grammar functions corresponding to ‘ - 리₁-’ and ‘- 리₂-’ of the 15th century Korea, respectively. For example, ‘★’ functions as the prefinal ending and ‘★’ functions as the interrogative ending in combination with interrogative auxiliary element.BR In the 15th century, ‘-리₁-’ and ‘-리₂-’ show different grammatical categorization, as the ‘-리-’ element was originally a combination of two or more morphemes, not a single morpheme, deriving from other grammatical elements. The element was drawn from a combination of a gerund ending and a copula, but ‘리₁-’ and ‘-리₂-’ were differentiated by which prefinal ending the element is being combined with. The two forms derived from the grammaticalization process of the interrogative endings and formed new grammar categories. Although they contain different semantic compositions, their properties indicates that they share the semantic function of the estimation.