The paper also offers a supplementary analysis of the two subtypes of the vague action verb, using the hybrid model of lexical conceptual structure and syntactic argument structure. This paper investigates the etiology of the contrast between Korean/Japanese (K/J) and Chinese in the availability of a quantificational/sloppy reading to the null subject. We attribute this contrast to the asymmetry between K/J and Chinese in the Case/topic marking system. K/J employs both overt subject/ object Case marker and topic marker, but Chinse does not have either of them. The latter language rather uses structural positions to code grammatical and topic relations. Though an object element in Chinese uses different positions (i.e., post-verbal and clause-intial positions) to indicate its grammatical relation and topichood, a subject element uses the same clause-initial position to do so. Thus, the element in clauseinitial position apparently regarded as a subject element is grammaticalized into taking up the marked role of a topic in this language. Mutatis mutandis, its null counterpart or null subject is only construed as a definite topic, which bars it from being interpreted with a quantificational/sloppy reading.