Abstract: “Ke neng”is a probability modal operator with the core modal meaning of ［+probability］.According to “scaling of probability valuation” in probability modality,the range-based regulation of “Ke neng” is “0<X<1”(X means probability,0 means negation,1 means affirmation).Speakers can accurately determine the probability valuation of “Ke neng” by adding degree determiners or co-occurring with other modal expressions.

Key words: “Ke neng”, probability, probability valuation