Much of our grammatical knowledge is represented through Phrase Structure Rules, which state explicitly all and only the possible combinations of the ______ of a language, for example, in English, NP→(Det) (Adj) N (PP) (S).

Much of our grammatical knowledge is represented through Phrase Structure Rules, which state explicitly all and only the possible combinations of the ______ of a language, for example, in English, NP→(Det) (Adj) N (PP) (S).

A.phrases

B.clauses

C.sentences

D.constituents

正确答案是D