There are many similarities and many differences between the elements of the post junctions, 'Yǐhoù', 'Ránhoù” and “Hoùlái'. These differences are manifested in the part of speech, semantics and usage of the three words. In terms of part of speech, 'Yǐhoù' is a positional noun, 'Hoùlái' is a time noun, and 'Ránhoù' is a conjunction. Semantically, 'Yǐhoù' and 'Ránhoù' can both express past and future time, and can also indicate the time when a general, habitual event occurs. 'Hoùlái' can only represent the past time. 'Yǐhoù' emphasizes the accuracy of time, 'Hoùlái' emphasizes the sequence of events, and 'Ránhoù' emphasizes the convergence of events before and after. In terms of usage, all three words have a front-matching and a back-matching, but they are different.