The first is agrammatism, exemplified by Broca's aphasia, sufferers of which produce speech that lacks functional categories. Chapter 16, 'Lexical variation and change', concerns lexical variation, and the concept of register and contact are introduced to explain this. Another important grammatical concept, aspect, is explicated with examples involving participles. Chapter 19, 'Sentence structure', examines in detail merger, a syntactic operation that combines words to form a phrase. A labelled tree diagram is presented as a convenient means to represent syntactic structure.
Coordination is employed as a test for constituency, and merger is constrained by feature checking.
The topic of Chapter 20, 'Empty categories', is perhaps one of the most contentious issues in contemporary syntactic theories. Thus, the derivation of syntactic structure in this framework is driven by merger and movement. Parameters appear to explain linguistic variation in this syntactic framework. Wh-questions in Chinese provide evidence for covert movement. Also explained is children's use of objective case with infinitives, and omission of determiners in non-finite clauses.