First, gradable antonyms such as kuaile/beishang 'happy/sad' were not considered, for the negation of a gradable antonym does not entail its counterpart (i.e., bu kuaile 'not happy' does not necessarily mean beishang 'sad').
the present study selected complementary antonyms, which are mutually exclusive (Cruse, 1986); the negation of one can be regarded as near-synonymous with the other.