... concept and it is expressed by many means : Lexicalisation, grammaticalisation, intonation, etc. However, in this thesis, we only focus on lexicalisation ( modal auxiliary verbs, lexical words ... are refered to "weak" and "strong" epistemic modality. Weak epistemic modality is grammaticalized with the verbs “can” and “may’. Strong epistemic 11modality is grammaticalized ... of Modality in some speeches of the president Obama(Phân tích tính tình thái trong một số bài phát biểu của tổng thống Obama ) graduation thesisfield: linguisticsStudent : Phan Thị ThuậnSupervisor:...