In the question form of “How A is NP", the role “A" is taken by the unmarked member in a
gradable antonym pair, the meaning
of which is not committed to either end of a semantic scale. Linguistic data shows that the number of gradable antonyms which can neutralize the contrast when positioned as “A" is very limited. This paper argues that the statement that “A" in “How A is NP" is usually “unmarked members" is too general and vague. On the basis of a review of the markedness features of gradable antonyms, this paper explores the motivation of
neutralization of the limited antonyms and forwards two conditions for the fulfillment of the neutralization, one being necessary condition: the semantic feature of the antonym should reflect the natural properties of things concerned; the other being sufficient condition: its semantic feature should be able to cover the full semantic scale of the antonym pair concerned. These limiting conditions are in fact the mappings of rules in reality onto language use, to be specific, grammatical rules and semantic categories are the mappings of the rules in reality onto language through the medium of human thinking, which reflects a basic principle of syntax: the semantic coverage of words remains in direct proportion to their syntactic functions.