Bukeneng' is the negation of modal of assumption. Therefore, it belongs to a strong set of 'impossibility', negates the modal. This form is a form that does not require a graduality of the meaning. Thus, by the nature of the word 'impossibility', it appears to be combining 'jue', 'juedui', 'genben' and 'yagen', which generally represent a strong meanings. On the other hand, 'buhui' is a proposition negation of assumption and has relatively weak meaning. However, the meaning is strengthened and weakened by the adverb or auxiliary verb. In other words, the meaning that speculates of 'buVP' with 'buhui' can form a continuous continuum from strong to weak. These 'buhui' allow the formulas of the adverbs such as 'jue', 'juedui', 'genben', and 'yagen' to reinforce the meaning. At this time, 'jue-buhui' is almost identical to 'jue-bukeneng.' Also, unlike 'Bukeneng', 'buhui'can represent aspect of habitual behavior and be used for future guesswork. The difference between them may not be a significant difference between the speaker and the listener. But if being asked to tell the difference, We can also point out that 'Bukeneng' is impossible and seems to represent stronger meaning.