The content of the paper can be summarized as follows: (1) The typical structure of nominal expressions in Mandarin Chinese is analyzed as [DP [NumP [ClP [NP ]]]]. (2) NP is a lexical category which describes the contents of entities or notions. (3) NumP is a functional category which denotes the number of entities described by a noun, and ClP, too, a functional category which makes nouns of Mandarin Chinese countable. (4) DP has the function of mediating between the description provided by NP and entities in the real world the description is applied to. It gives referential meanings such as “Definite”, “Indefinite”, and so on. (5) When D is lexically filled, DP has a definite referential meaning. A null determiner functions as an existential operator to produce an indefinite meaning. (6) A DP with a null determiner can appear only in the lexically governed position due to Empty Category Principle. (7) A sequence [Num+Cl+N] can be interpreted as having two structures, a DP with a null determiner and a NumP. (8) Bare nouns can be interpreted as “indefinite”, “definite”. An indefinite bare noun has the structure of [DP e [NP N ]] and a definite bare noun, [DP Ni [NP ti ]]. (9) In general, pronouns and proper nouns always carry a definite referential meaning and so can appear in D. (10) The pronouns and the proper nouns appearing in N do not denote a specific entity. Their meanings are similar to common nouns which denote types or kinds of entities. (11) NP"s can not be used as an argument but as a predicate.